Nice! I like how this piece seems to encompass a lot of conflicting emotions -- it has the darkness of a villain theme, but it's also rather pensive and even defiant/hopeful in places. That's a lot to cover in a short theme! Also, the sword sound effect was a fun addition that helped set the tone.
In terms of references that are coming to mind, I'm definitely getting some "Lux Aeterna" (Clint Mansell & Kronos Quartet) vibes with the bass/cello part. The opening also reminds me a bit of music from some '70s era martial arts movies. I know neither of these were probably intentional on your part, but I think it speaks to the strength of the piece that it seems to be so many things all at once. Good work!