Tools of madness

Blade of healing: This claymore of warped design looks quite deadly with apparently razor sharp edges. But in the hands of someone mad it will heal wherever it would cut. Great wounds will be magically healed by swinging it. If done fast enough even a head/limb may be reattached. But only in the hands of a madman, in anybody else it's just a sharp claymore. There are tails of 'healers' appearing and running around after a battle wildly flinging the sword on the fallen. These poor, misunderstood, helpful souls don't usually live long enough to use their own weapon on themselves.

Sledgehammer of fine repair: The gnome upon inspecting the broken watch picks up a sledgehammer and promptly brings it down upon the fine machinery. Not only does it not hurt the delicate gears it actually repairs them. But the sledgehammer only works for delicate repairs; a wall would get the opposite treatment.

Fungi/rust of building repair: This fungus heals the wooden structure and this rust regenerates the metals in large buildings. The effects work over night and anyone who knows about buildings will be convinced that these are the varieties that actually hurt the buildings by corroding them. Good luck convincing the chief architect why you are rubbing that slime on his building.

Scissors of mending: Nicely mends thorn or cut things with a reverse scissor cutting motion. There remains no sign that anything ever happened.

Torch of de-incineration: Keeping the torch pressed to ashes it starts to regenerate the material that was once burned. Dropping it on a campfire will generate firewood, stirring cooked food will make it raw again and leaving it next to an urn will make you have to explain the corpse...

Cristal ball of never going to happen: This tool of telling the future is very accurate. It will tell you an event close to the future you are interested in that will not happen under any circumstance. A group planning city wide arson will not find out about their plan being a success but might see a little orphanage intact. There may be hundreds of reasons why this might happen this way, the group failing in their task, wind blowing away, rain, being protected by a group of adventurers, home of a demon etc. But try as they might the group cannot change this fixed event in the future.