You shouldnt trade your Joker for something likes of Belobog. Get a SR spirit or something, you could get way better spirita since this is very hard to comeby.I just thought that jokers work on every light spirit once they hit mix level. Isn't that how it works? Does that mean my inti and Miroku will also not work with joker of light if you want to level break them?
And I had no idea I could get decent trades with this joker. This could fix my problem with Belobog.
You can use Joker on your Belobog to break limit but like others said, it would be a waste since you should do it with a better spirit.