Underrated Skills?

Fire boost: This is an extremely underrated skill on high hp units. One way I can see It being used is if you get a +hp Nowi and give her the hp +3 seal, she reaches 51 hp and gains a lot of survivability and extra damage, and with Quick Riposte can kill all units except emerald axe users, TA greens, and Effie/Julia. She also one shots all falchion users this way. Any other Underrated skills you guys can think of?