Elemental Stones and Converter questions

[Kyasharin]

Okay, so. Question one. If I have 10 of, say, Red Bloods, and I wanted to make a Flame Heart, how would I go about doing that? Does that require a Blacksmith? Or is there some NPC somewhere that can do it?

Question two, about the elemental converter things, that I just now found out about. If I don't actually have a weapon, does the elemental converter work?

Many thanks in advance!