This link might help you, it's an article on spell creation written by a DFRPG playtester and it just so happens to include a flight spell which I'll quote below for convenience.

Up, Up, and Away!
In the Dresdenverse, spellcasters usually don’t try flying spells, and there’s a paragraph at the bottom of p282 of Your Story that explains why*. It’s a matter of control – just because you have the ability to fly doesn’t mean you have the expertise to safely move through the air. And given the penalty for falling from any sort of height, there’s a real danger inherent to slipping the surly bonds of earth.

That said, building a flying spell is pretty simple, if the GM is going to allow it. Personally, I would let someone get away with it if he or she built the character to show that he or she had spent time mastering the intricacies of aerial movement. Here, I’m thinking a minimum of a stunt to reflect the ability to use Athletics for flying, and preferably both the stunt and an Aspect to show the time and effort expended in gaining this off-beat skill trapping.

The guideline for gaining new powers by using magic are laid out in the sidebar of p283 of Your Story: what you need to do is transform yourself into a form with the new powers. You need shifts of complexity equal the amount necessary to kill a target, plus you need to spend Fate Points to gain the temporary powers.

So, let’s say Harry wants to be able to fly, binding the winds to hold him aloft and move him around, and his benevolent GM has okayed the attempt. In my mind, though it’s not listed anywhere in the rules that I can find, transforming a willing target should be easier than an unwilling one, so for purposes of this spell, Harry has to meet a complexity equal to all his possible consequences plus 1, but doesn’t need to overcome his Stress Track (because he just decides to take all consequences rather than Stress), and his defense rating is locked at Mediocre (+0) (because he’s not trying to resist the spell or defend against it in any way). This sets the base complexity for the spell at 21: 2 for his minor consequence, 4 for his moderate consequence, 6 for his severe consequence, 8 for his extreme consequence, and 1 to take him out. The taken out effect becomes gaining the ability to fly.

Duration becomes very important for a spell like this. I’d start the default duration at a single scene* (15 minutes or so), so if Harry wants to be able to fly for longer than that, he needs to boost the complexity as well. Let’s say he needs to be able to fly for a day. That increases the complexity by 5, stepping him up the duration ladder from 15 minutes to a day. Total complexity comes out at 26.

In addition to this complexity, Harry has to pay Fate Points for the power, in essence temporarily lowering his Refresh to buy the power for the duration of the spell. While there is no Flight power, there is Wings, which is a -1 power. That’s close enough for our purposes, so Harry needs to pay a Fate Point for the power. If he needed to fly super-fast, he’d have to pay the Fate Point for Wings, plus another 2, 4, or 6 for the desired level of speed power. But let’s keep it just to flying.

Now, Harry’s got a Lore of Good (+3). That means he needs to make up a whopping 23-shift deficit to be able to cast this spell, and he needs to have at least a single Fate Point left at the end to pay for the Wings*. For convenience, let’s say he goes through the same routine he did for the Magic Parachute spell above, giving him +10. After that, he buys some special incense for the ritual (Resources: Ritual Incense), gets Listens-To-Wind to bless his falcon feathers (Contacts: Shaman’s Blessing), does a little research into the wind patterns over the city to find the optimal place to get the attention of wind spirits (Scholarship: Air-Flow Map), fasts for a day to purify himself (Endurance: Ritual Purification), spends an hour conducting a centering meditation (Discipline: Focused Mind), and then drives out to where he’s going to cast the spell and scares off the muggers in the park so he can work uninterrupted (Intimidation: Quiet Workspace). That bumps him up to a total of +24, so he’s set to cast the spell.

Dealing with so much magic, there’s a real potential that, if things go badly, Harry’s going to be in a world of hurt, so he’s going to go slowly with the actual casting, drawing one shift of power at a time. With his Good (+3) Discipline, that means that he needs to roll -2 or better on each of his 26(!) rolls to get the power he needs and take to the air. He’s only got a 6.2% chance of blowing any single roll, but with the large number of rolls, he’s got about a 16.8% chance of succeeding on all 26 rolls without needing to spend a Fate Point or take some backlash*. Not an easy spell.

Final version of the spell:

Quote

Rite of Icarus
Type: Thaumaturgy, transformation

Complexity: 26; can vary depending on duration

Duration: One day

Effect: When the caster completes this ritual, he or she must pay one Fate Point. The caster then gains the ability to fly, as per the Wings supernatural power, for one day. Unless the caster has some training in moving aerially (reflected by an Aspect and/or stunt), the caster’s Athletics is considered Terrible (-2) for purposes of moving by way of flight.

Variations: This model can be used to gain any reasonable power, subject to GM approval. Fate Point cost is equal to the refresh cost of the power acquired.

 

Well that does make sense austinmonster, but what about when Molly makes one of her friends fear drugs? You could argue the fear itself doesn't prevent them from choosing drugs, it's just makes them more inclined to avoid them.

Of course that was a permanent change rather a mild modification, but bear in mind that in YS it does state that the love potion is in a grey area.

An illusion of beauty could change someones state of mind but it's the minds response to stimulus rather than a forced change. Perhaps the love potion was more like a chemically induced state than mental magic, affecting the body rather than the mind directly. Music can arouse powerful feelings in someone and, with magic, perhaps that effect can be magnified without it needing to be mind control.

Hey, I liked DMW's take on it mostly, however I also liked the were-form idea so I thought I'd combine the two, plus I wasn't keen on including evocation because, as flexible and powerful as it is, it also puts a large constraint on the skills required so I came up with this.

In human form you'd be marked by power, have bestial senses relating to the hunt (keen sense of smell, great night vision etc) and you'd have the ability to recover from injuries. You would also have some power over nature through breath weapon, allowing you to launch projectiles (the form is up to you, but I'd advise something hunter/nature related) as well as do manoeuvres that you might not otherwise be able to do. Because this relies on weapons, you can max that out without worrying about conviction or discipline and it doesn't cost mental stress, it's not as powerful as evocation but with your spear and strength you are far more effective in close combat anyway. This means you're quite effective even in human form.

In beast form (picture below to help you picture it) you'd gain strength, speed and toughness making you pretty lethal, plus the idea of turning into 'The Hunter' is just cool.

Finally the spear is a powerful weapon with true strike, plus with glamours you can veil yourself, disguise the nature of the spear to mortals (allowing you to carry it in public hopefully) and lay hidden hunting traps.

Skills required - Weapons, and then either Deceit or Discipline.

[-1] Marked By Power (Erlking)
[-1] Echoes of the Beast (The Hunter)
[-2] Inhuman Recovery
[-2] Breath Weapon (allows you to fire hunters arrows, porcupine spikes etc, plus nature manoeuvres like nearby branches knock them to the floor, brambles and roots wrap around their feet etc)
[+1] Human Form (You grow stag like horns, cat eyes and cloven hooves
- [-2] Inhuman Strength
- [-2] Inhuman Speed
- [-2] Inhuman Toughness
- [+3] Catch - Cold Iron
Total is -8

Item of Power:
- [+2] Hunters Spear
- It is a Weapon:3 spear, unbreakable etc
- [-1] True Strike
- [-2] Glamours
Total is -1

Total refresh cost of -9

What do you think?

Plus, Jedi are constantly being disarmed (or dis-handed) throughout the films, it's a common theme.

If I am following your querry correctly, then model it after Way of the Bow under Guns, which enables you to use Guns for bows and Craftsmanship for bows, and provides a +1 damage with bows.  My point is, outline it for a specific weapon category (Swords, Clubs, Axes, Chains, Vacuum cleaners, Hats...although we already had a thread on that one), keep the bonus to +1, and I think you'll be alright.  I don't have my books in front of me to verify this, however.  Gimme a sec to check...yeah, that's pretty much how it's meant to work.  It does say under limited circumstances (their example is their Guns stunt where you're also outnumbered, but if you limited it to a very specific weapon...long sword, instead of just swords, for example...that might cut the mustard...heh...more pun damage).  Alternatively, if you want a bigger boost (+2 with a broad category, for example), you could validate it via the expenditure of a fate point, ala Killing Blow.

As has been said a few times on this forum, a disadvantage that isn't a disadvantage isn't worth anything. Limiting the character to only one weapon isn't a disadvantage if he takes it everywhere with him and the only way he'd lose it is if the GM takes his weapon away... which just isn't at all fun. A better version would be something like duellist - 'you get +1 to your attack roll when your opponent has a similar weapon' which limits you to the opponent you fight and is quite flavorful. It doesn't stop you from carrying around a sword, an axe and a knife though Or perhaps knife fighter - 'you get +1 to your attack roll whenever your weapon is weapon:1'. This is also flavourful and again, there is a clear disadvantage, you aren't as accurate when you use larger weapons.

Vultur - I like! Simple but effective

Fandraen - Well it makes sense but I know it's a controversial subject. It will require a catch, probably an emotional catch like 'fear' or 'lust', something which could actually be abused. I'd also say that it should automatically have the extra catch of 'self-inflicted' so that wizards can't abuse this massively. That does reduce it's utility a lot though.

Oo thank you, I've always mis-read that! I sometimes wish the rules were a little simpler and more uniform. I was confused by the Whirlwind spell on YS295 which describes a sticky aspect created with evocation. Perhaps it only means that it lasts an extra exchange.

I think that potions can be used to achieve certain effects using skills as a guide to it's strength value - for instance an escape potion that allows you to move to any zone as if you had an athletics equal to the strength of the potion; I don't think it can boost a skill though, at least not in any significant way without causing damage - see biomancy:

potions can be used to boost strength, speed, perception, and other functions of biology— provided that the body being boosted can withstand the stresses of such an effort. Just because muscles have been supercharged to lift a small car doesn’t mean they’re built to withstand the damage that would do; inflicting consequences on the beneficiary to boost spell effectiveness is not uncommon (Torn Muscle Tissue, etc.)

So a potion could boost alertness by a little bit by creating a relevant aspect, but if your own perception is jumping into double digits, expect to suffer from some serious mental or physical issues whether it's paranoia as you can no longer see everywhere, or cataracts as the UV light toasted your suddenly incredibly sensitive lenses.
Improving your guns skill would do the same thing, if I were GM I would happily state that your character has suddenly realised how evil guns can be and is terrified of them, or he becomes so cocky that he spends the rest of the gun fight doing trick shots that knock peoples hats off, bounce guns out of peoples hands and so forth.