• The Bonepicker's Blade is definitely a unique implement of choice. Dull as a rock, this blade cannot be sharpened or honed and is a poor choice in any kind of physical battle.
• Its only apparent use outside of adding absurd weight to your carry for its size is its ability to stab incorporeal creatures and beings, and stab them righteously.
• It does also seem to be curiously immune to damage - it may not be able to cut, but it can block another blade quite well.
• Fae also hate this blade as it is heinously potent against them, effecting them twice as bad as iron.
• The longer this blade goes without seeing action or use, the heavier it becomes to the owner/carrier out of spite. It just wants to stab ghosty things, it's not exactly asking for much.
• This blade holds no allegiance to anyone or anything and can be used by any type of magic practitioner except for fae and ghosts - obviously.

At best guess, this was a beginner alchemist's attempt to make something heinous but fell quite short. Instead of crafting a blade of unyielding strength and merciless edge, they forged a dagger of unwitting stubbornness and a bad sense of humor - a bit like Uncle Joe. Use it well, or don't.