A limit or timer wouldn't help. All it would mean is that you'd get time to build up a even more super-duper suit before some newbie naked thief glass-swords you and takes it.
Furthermore, even if you could only use it once per character, ever, people would just delete their newbie naked thief and make a new one.
There are so many ways to abuse this item. It should just be removed. It does not encourage pvp, it will simply drive pvp'ers off the shard.
These are really the most bone headed thing I've ever seen added to UO.
They were cool in Ultima IV, but if you knew the bug (and everyone did), you could oneshot all the dragons and it was even used to kill Lord British. That was overpowerd and took away from the fun of the game, but it was a PvE game. Putting such a thing into a PvP game is coo-coo.
Even if it was limited only to use in PvM, then people would use their newbie naked thief to oneshot the dark father, or dreadhorn, or the stygian dragon, or whatever. Those are supposed to be hard.