I had the idea of a character like an adept in Shadowrun, who uses magic to increase his melee attacks. Basically I gave him a stunt that let him use fists instead of discipline for close combat spells like a melee block or an enhanced fists attack. The numbers are the same, if I cast a spell on an opponent using discipline or fists, but fists are restricted in range, of course. I even thought about having him use fists to cast rituals, because he would have some sort of martial arts background, so he would use the motions from his martial arts style in his rituals.
You could do the same with a weapon stunt, so instead of channeling force through his body to hit his target (like my guy), he shapes the force into a weapon he uses to attack. It would still have the same rules like a normal spell, only you use weapons instead of discipline (and of course the range problem is there again). If he uses his magic like that, it is only fitting that he will not be as good at conventional evocation attacks (read: fireballs etc.), which probably should be reflected in an aspect like Harry's "not so subtle, yet quick to anger" or Molly's "subtlety is its own power" aspects reflect the parts of magic they are good at.
An aspect like "ethereal sword" could represent that for your guy. If you do not cast a spell, you can just say the sword is still there, because it is his style, it just doesn't do anything else then give you a reason to use the weapon skill in any fight. And maybe allow you to invoke your aspect on your weapon skill, of course.
A totally different approach:
Make the Sword a Supernatural power, that lets you use a weapon:2 magic sword as described above. It would be the melee equivalent of the breath weapon power. Somewhere someone proposed using breath weapon as a power for a fireball slinging wizard, so he would be more effective in combat, because he would not take stress from casting. The Argument was, that the wizard is so good at combat magic, that it basically is part of his nature.
Here's how I would stat it:
Ethereal Sword [-2]
Description: You are able to create a magical weapon in your hands to attack a target in your zone)
Note: You'll need to lock down this magical weapon to a single type of effect - e.g. a sword made of fire, ice, lightning, etc. - when you take this ability.
Skills Affected: Weapons (this is treated as a melee weapon).
Effects:
Magic Weapon: This is a self generated Weapon:2 for melee range. As with any weapon, you might be able to use it to perform combat maneuvers if you can justify it.
Parry: You can use your weapon skill to defend against a melee attack instead of dodge.
Might be especially powerful if combined with a weapons stunt like Wall of Death
