We can argue the "healer" already had one, when she taught Cross how to fight like an undead, and the elf could be argued to have had hers when teaching Cross "Magic Stocker" and versatile/creative magic usage IIRC.
Yeah, it wasn't solo, but it was an arc focused about them imparting Cross with their own individual specialties, which also demonstrated more clearly what they are capable off.
Only the dragon woman was left, since we hadn't seen her do much specialized training for Cross besides body strengthening sections on other training sequences.