Wait. Does this mean that veils created by potions only last one round? Or that what if I want a veil at say 4 for say 4 rounds I would need 16 shifts of power? I think the rules specify otherwise. A veil replaces a roll of stealth... Or does this mean that the 1shift duration thing only applies to evocation? If so what about anchored wards? I would appreciate clarification.
This can work as a stealth skill replacement. This works nice if you only have single task to complete: sneak by the guards. They get an alertness and it has to beat the Power of your item. If you succeed, you get by - end of task/conflict. If there are multiple rolls, a block on perception/veil is best. If it's in a drawn out conflict, it should probably have duration and last 1 exchange/shift. If you are outside of a conflict, veils can last as long as they are narrative appropriate (since 'exchanges' don't really apply out of combat. So it could last for several minutes, a whole scene, etc...and be useful against multiple alertness rolls. There's a comment in the margins on the evocation 'veils' section of Your story where Billy suggests evo veils should last a scene.
Wait I've re-read your post and I realize I misunderstood.
Lets say then that I have a magic item that replaces my initiative x frequency per session. Does each frequency last a scene (say an entire fight) or a round? So if x is 4 and the fight lasts 5 rounds on the fifth round the item would be used up.
Initiative is only applicable for the first round before the fight starts. I'd make it an alertness skill replacement or make it an 'alertness' related aspect.
The skill replacement can be used from anything to noticing an ambush, initiative, spotting something important. But it only lasts for one use of the skill roll.
A maneuver would give you an aspect. You can use it to boost your initiative by 2, reroll your initiative, maybe even give you a temporary minor power (like the initiative boost from inhuman speed) but that last thing depends on the generosity of your GM.