Wow, very nice deal. My L32 SoM+4 Spear on Athens cost me a nice 60M.
However, about your question, I would say leave it as it is. As you most likely already know, every weapon already has a built-in success rate. If you've tried 10 Elixirs, and it hasn't gone past +2 yet, then your Sword may just be one of those unlucky ones. If you're wanting to sell it, I think you could make a nice profit off of it right now - if you try to pimp it out, and it fails, you'll lose some of that profit.
Or you could just keep it, like Cerus said.

I don't think the L32 Sword looks that good, though.