I think it would be neat to have some form of portable generator, which consumes fuel from fuel cans to generate EU while in your hand/off-hand. Possibly it could also only provide power to the hand/off-hand slot?

A possible upgrade could be a nuclear version, which has a small reactor inside it like the nuclear jetpack, but is turned on/off manually and provides EU to whatever is in your hand (if anything)

the idea was already thought of once during the 1.10.2 version but was never implemented because the way how the Inventory Energy Transfer works is not really making this a good idea.
Inbalance is a really big problem. Because the way how ic2c shares energy in your inventory makes it also work with armor etc.