Celica appropriate sacrifice for Grima...what about aether over ignis?

I solved my A skill issue for Grima by sacking off my 3rd and final Celica for DD (all 3 were crappy IVs and the previous 2 went to xander and Fjorm who dropped ice mirror/shield pulse and picked up QR/iceberg). For the 1st time I plan on 5* fodding a chrom for aether to a worthy unit that can fully utilize it quicker than it's standard high CD. Grima for me is +res/-hp btw so kinda like both def and res over 30 but can now factor DD to go with vengeful fighter on enemy phase. I ask anyway for feedback if aether is great for him long-term.