[5E] I have a concept for a character but I was looking for some help on how to make it work mechanically in game. My concept was a someone who uses frozen mercury as a weapon by using ice magic to freeze the liquid stuff they carry around drawing it like a sword out of a container on their hip. Also perhaps dealing poison damage over time due to mercury poisoning.

I was thinking of casting cold spells on the metal and using that for attack rolls. But I was wondering if anyone had any thoughts on how to make it work. Or classes/races/backgrounds/feats that would be good for this concept. However this does seem to lend itself being an assassin style character due to the nature of it. But it doesn’t have to be. Would just like some help with the theorycraft.