Lucina and Luna

I would definitely say no. Lucina is a very rare unit and besides that very powerful (not the best red unit anymore but still great. I still use her sometimes). For Luna fodder I prefer Frederick and Catria because they learn that skill at 4* and are a lot more common than Lucina (3*-5*). So I would wait for them and maybe stay with the vanilla Skill if that unit has one or go with Moonbow instead if you have that available.