This has been an issue for, what? Two years now? I never see any mention of this by devs in general or in the Known Issues thread, but it's a major pain in the ass.
For clarification, if you have an item equipped that grants an extra use of Rage, Uncanny Dodge, Turn Undead or Action Boosts, when you remove the item, you lose however many charges it granted. This would be fine if it occurred only once, but it happens each time you remove the item, and occurs each time you die as well.
So, for example, the Frenzied Berserker set bonus from Knost's Belt + Encrusted Ring from Tower of Despair grant barbarians an extra Rage per rest. If I take the belt off to give myself a Greater Heroism from a Planar Gird, I lose a Rage. If I die, I lose another Rage. If I then want to rebuff from another Planar Gird, I lose another Rage.
If I die, get raises, and die again, I just lost 2 rages, not counting any rages I was actually activating.
If a fighter is wearing Verik's Necklace, which grants extra action boosts, and is running through the Subterranean, and has to swap back and forth between his Beholder Optic Nerves, he can quickly remove all of his action boosts just from swapping items.
PLEASE can we get this fixed?!