Shape Shifting Item of Power

[ways and means]

I was working on an item of power which is a full sized rapier which can turn into a black key (to one of the seven gates) for ease of storage. How would people stat such a power and how would it effect the refresh rebate for an item of power?

[Eldritch Donut]

I think it sounds like a fairly minor thing. Maybe a -1 refresh change.

[Gatts]

Depending on the speed at which you can do it, it could just be a +0 power. You gain the ability to keep it around with you, hidden, but you now have to wait an action to actually use it. I'd say that balances out. If it can change as a supplemental action or faster though, it needs to be about -1.

[ways and means]

The thing I am not sure about is does it reduce the item of power bonus for a large weapon (+2) if it costs a point of refresh itself to change shape.

[sinker]

To be honest that sounds like more of an aspect than a Item of Power. The character could reasonably have a rapier, so there's no real benefit there and holding a key to one of the seven gates seems like it could be compelled just as often (if not more) than it would be invoked. Unless it has other powers I would just give the character the aspect and call it done.

[Gatts]

The thing I am not sure about is does it reduce the item of power bonus for a large weapon (+2) if it costs a point of refresh itself to change shape.

I'd entirely forgotten about that. Then yes, +0 refresh to be able to do it as a Supplemental action, and you lose the benefit for it being a large weapon. It's fairly self balancing.

[Haru]

Or you could just give it "human form" or "human guise", depending wether or not it loses its powers while transformed.