I (DM) once randomly rolled the coolest bow ever for a hollow-glacier-dwelling lich's treasure hoard near the end of a high-level campaign.

I'd rolled a composite longbow, rolled 'special ability and roll again' five times before landing on +4.
The special abilities rolled were Thundering, Bane x2, Holy, and Unholy. I wasn't going to make it an epic weapon, so something had to go.
For the first Bane I rolled evil outsiders. At that point I decided to make the other Bane for good outsiders, and dropped thundering.

I named the bow The Destroyer of Heaven and Hell, as it strikes as a +6 (epic) weapon against good and evil outsiders so it can overcome every type of damage reduction (with special arrows, if needed).

Only a character who's neutral on the good/evil axis can safely wield it. One player always plays neutral bruiser-types, so he chose to keep that as his ranged weapon for when he needs one. I don't think he ever used it, as there was just one more short adventure left in the campaign after that, but everyone thought it was the coolest weapon they'd ever found.