maneuver spells take a +3 shift

Speaking of math, I thought I'd throw this in. Maneuvers are only 3 shifts if they're on the scene (or target friendlies, I guess). If the target is an unwilling sentient, then you need a number of shifts equal to their appropriate resisting score. (Athletics for a maneuver meant to trap them, for instance.)

Apparently I misunderstood what you were looking for. I was just giving you my thoughts and suggestions on how the current grapple rules could solve your problem.

I feel like death curses would generally tend to be much more malicious than that. Important factor I thought of though is that a Death Curse is essentially a Thaumaturgy ritual that uses all your stress and consequences (or arguably just what you have left), so maybe just try to figure out what those shifts get you in terms of effect and time. Just a thought.

Thank you Umd for those rote ideas. You gave me the visual I need with the mechanics. How do focus items boost skills?

It's contextual. You use Weapons as your 'targeting' roll for magical attacks, so where if your sword is a +Power Focus Item you are effectively increasing the potential Weapon rating of your attack (without taking additional mental stress), when your sword is a +Control Focus Item you are increasing the accuracy of your attacks. If you're not doing magic it doesn't help at all; hence my comment about using stunts instead of magic.

I was thinking of looking at Butchers other series. If I remember correctly one of the characters had a metal spirit and was a swordsman.

Indeed. They basically use it to enhance the metal, as far as I can tell. So they an make it harder and sharper to the point where they can cut through normal steel like butter (basically, what you'd be doing with a magic-as-swordplay attack). You might be able to get some other ideas out of it though. I've only just started Cursor's Fury, myself.

PS: What do you mean by "better-than-stunts"? Moving a trapping in all cases is a standard stunt effect.

YS implies that they should be restricted when describing it but the examples don't bear that out. I'm not sure I'd allow it unrestricted in a game I was running (it feels a bit too powerful) but, meh. I concede the point where the RAW is concerned.

Okay, so before I get into trying to help answer your questions (and meaning no offense to the original author) remember that this is a homebrew power. Personally I think tacking on 2 better-than-stunts (switching the skill trappings in ALL cases) as "extra benefits" for no additional cost is a bit much. IMO, if your GM even allows it it should probably be -5 or even -6.

How does metal based evo and thaum work?

That's kind of up to you. Obviously any "summoning" type effect is going to use metal (as opposed to fire evocation blasting with fire, a metal evocation might send a wall of blades; a shield make take the form of a literal shield). On the other hand, more conceptual effects (water is entropic, for instance) would depend on the properties of metal as an element. You could just go from the properties of metal or you could try taking it as Metal from Wu Xing. Wu Xing is similar to other 5 element systems but replaces Air and Spirit with Metal and Wood. Wood has strong spiritual associations but in Japanese culture (if L5R is to be believed; I couldn't find any quick support so I'm not positive) the katana is one of the few non-human things that contains significant elements of Void (Spirit) and thus Metal could be considered Spirit. I can't really say which set of associations feels "right" to me, but if you decide to go that route pick a pairing, borrow the appropriate DF associations with the given element (Air or Spirit), and explain it to your GM.

Does evocation work in concert with melee (if the focus of the magic is swordsmanship based)? If so how would it work? If not how should I use magic to enhance melee or melee to enhance magic?

No. Or yes. So, with few exceptions (reflexive blocks; the question of which already has several threads dedicated to it) any sort of magic is an action and you can only perform one action per exchange. However, what this particular form of Sponsored Magic appears to represent is the idea of using melee AS magic. When you cast a spell, you're not doing either; you're doing both... you're just doing it using the mechanics for casting a spell. Another way to look at it might be the idea of "secret techniques" or ninjutsu often found in anime. And, hey, you can use Focus Items to (effectively) boost your Weapons skill above the normal possible. eg...

Death of 1000 Cuts: Attack evocation. In a normal attack you use your weapon's Weapon rating. Since you use Weapons as your Control(/targeting) skill, this is essentially an attack with a Weapon rating equal to your Power (Might); unless you choose to define it otherwise.

Blade Wall: Block evocation. In melee, you might be able to 'dodge' with your Weapons skill normally but with this you can even block incoming projectiles or magical attacks (in theory).

As for enhancing ordinary melee, the best way to do that is Aspect maneuvers. Of course, you're probably better off not wasting your magic on this since you can do it mundanely...

Overall if you just want better melee you might be better off with Stunts, but I hope the above helped give you some ideas of how magic and melee might work together.

What rotes would you suggest for this sponsored magic to work cinematically and mechanically?

The above would be good places to start.

What thaum should he use...biomancy...divination...crafting...summoning etc (I see the line about summoning spirit warriors). What would "tapping" into "legends" look like?

Erg... okay, so biomancy is a field of study. You can't do biomancy. You might be able to do some of things biomancy does, but you can't do biomancy. For the rest... yes. The real question of magic (sponsored or otherwise) isn't "What can it do?" but "How can I make it do what I want?" Divination? The combined wisdom (or ghostly senses or whatever is relevant to the situation) of thousands of legendary swordsmen. Crafting? You're probably pretty good at making swords... what might a legendary sword be capable of? (maybe start here: http://en.wikipedia.org/wiki/List_of_magical_weapons). Summoning? http://en.wikipedia.org/wiki/Dragon's_teeth_(mythology) http://en.wikipedia.org/wiki/Terracotta_Army It's all in the imagination.

Then again, if you must NOT use a power you bought in order to stay alive, you've done something wrong in character creation. Not to mention, it takes the fun out of the game.

I take your point, but the game actually does this a fair amount. Of course, not all powers are going to be useful in all circumstances (which is why you get to trade FATE points for them) but more there are a number of powers that do this explicitly and don't scale well (like Human Form's Rare or Involuntary Setting). "The Catch" is another good example; you get the same buyback for your catch no matter how much you had to spend on the ability (and no matter how improbable narratively speaking, inevitably the GM is going to throw something at you that satisfies the catch just because he knows what it is).
But really, think of it like this; if you're dependent on an outside source of energy and you're going all out all the time you're pretty much inevitably going to run out of energy and probably in short order. You can always spend consequences to reduce the stress (and avoid takeout), plus the attack is reduced by a discipline roll so even 10 points of Powers with a 5 point Discipline doesn't mean a takeout without using consequences. It might mean only using them every few scenes, though. I would probably reinterpret it as a takeout triggers a feeding frenzy (undeniable compel to feed) or remove the track and just treat each attack as a maneuver for feeding frenzy with an automatic compel.