Larcade no diffs if Sting has sampled pleasure. If not, it would still be rather easy, but the fight might last a little longer than Kagura's.
Firstly, Lacade's light is the source of his power, but his actually magic seems to be pleasure and pain. So perhaps Sting cannot eat this magic.
Secondly, Larcade was able to block Kagura's slash, and then redirect it somehow. If Larcade does this to one of Sting's White Dragon Slayer attacks, sting will get hit by his own element and thus he'll probably not get damaged that much.
Tentacles are still in play, so Sting will have to do the same as Kagura to avoid those.