On my level 1 character Witsplinter does less base damage than other daggers that are commonly available. The enchantments don't seem compelling to me.

Since this is a unique artifact, I assume it is supposed to be a good weapon. Is it?

Maybe once you improve it? Rare weapons aren't always "best", just "rare".

If I'm going to improve a weapon I might as well use a dagger that has more base damage and sell the Witsplinter.

I just want to know if there is any reason not to sell it.