Cover reads:

Conveying a combat-oriented Cover to a PC at the Power-level of the Demon... is very deadly stuff.

That's all I'm saying.

A sword that confers cover converting the wielder into a mighty warrior does tire while in combat, as expected, with each attack or defense using the cover fatiguing the demon.[1]

Note a demon's cover gives the user skills associated with the given cover, but that doesn't mean the user automatically and instantly gains the contacts, benefits or similar associated to it.

A Passer demon can use it's Cover to avoid being identified as a Demon [2]