No, it doesn't have exp mod but it has wpn stats + level mod.
Max level each wpn can have = 9.
To reach level 9 with the same wpn, you have to finish 99.999.999 battles, well.. good luck with that lol.
If you want to unlock arts faster then change the Battle rank to 999.
If you want to level up your other charaters faster then change the battle rank to 0.