Re: Rules to ignore, or replace
I still think you are over analyzing it.
Take a Revolver. Still "Costs END" even though it may have charges, so it has to be "visable."
Hearing: The BANG! of the powder igniting and the bullet going super-sonic.
Sight: The muzzle flash and powder ignition ... But it's hard to see in a well lit area unless you happen to be looking at it.
Smell: The smell of burnt gun powder ... but it's hard to smell unless you are close anddown wind or have heightened smell. It can also be overpowered by other smells, like a sewer.
Perceivable, but to differant extents.
I don't think when it says a power must be "percievable" it means "blatantly perceivable." I don't have my book with me, so I can't check the exact wording.
And as an aside: Shapeshift.
Just because you can make yourself look like a tree, doesn't mean you would feel like one when touched, or sound like one when struck.