If you have other champs you want/need to rank up then hold off, but definitely rank him up eventually
You can also apply the 5* prefight and then enter the fight with the 6*. But torches awakened is hardly ever used and he does fine without it
Rank him up
Rank him up P. S-thise hits taken are intentional, if u know how to use torch then pls don't ask why I took them on my face