The trick to allowing extremely powerful items in your campaign is to multiply the power level by the duty cycle of possession by the PCs versus time spent missing or lost. If an artefact is 100 times as powerful as a typical item that they might possess all the time, simply make sure they only have it 1% of the time!
R2-D2: I'll sever Princess's chain with my shock probe.
Leia: Are you crazy?! Doesn't that do like a bazillion dice of damage?
R2-D2: What, this thing?
Leia: You lost the Orb?
R2-D2: No, I misplaced it.
[SFX]: < boop doop bip-buzz-boop-deep-dooby >
Leia: It's not called the Misplaced Orb of Phanastacoria.
C-3PO: Jabba's droids cavity searched us.
R2-D2: They literally cleaned us out. Periscope, thruster control circuits, flux astrolabe, hyper-sextant...
[SFX]: < doing ziwhree bizang zik-fik-jang bop pow spip-ting-prow spip-kuku-prow ziku-ting-prow >
Leia: Why didn't they take your shock probe?
R2-D2: I convinced them I might need it.
[SFX]: < doop eevoo-pating doop whir >
Leia: As a waiter?
R2-D2: Some people don't tip.
[SFX]: < niding boop fobuzz-pok >