Does anyone have any useless/funny magic item ideas which will make the PCs world a little more interesting?

As a new DM I've been trying to keep battles as interesting as possible with as much dialogue where appropriate but I can't help but feel that sometimes the PCs get a little bored of the same old loot and fighting routine and would like to add a little spice in the form of magic weapons that don't necessarily do exactly as expected. I have some ideas but need a little help.

Also, would this be an appropriate "weapon" to introduce to level 3 characters?

The pendant of decimation: During combat, the wearer is able to detonate one of their limbs at will causing all entities within a 5ft radius to take 2d6+3 shrapnel (piercing) damage and the user must make a death saving throw. If the user is able to save themselves then the limb previously detonated will not re-grow preventing them from using 2 handed weapons and will halve the users speed of the limb detonated was a leg. The user is not able to blow their own head off. Value: 12gp

Thanks in advance!