Strago has Grand Train, Big Guard, Step Mine, and a weapon called the Heal Rod that fully heals one character if you attack them. Relm doesn’t have any unique spells, any useful weapons, or a useful character skill. And once again, if you’re far enough in the game for Big Guard and Grand Train to be useless, Relm can’t do anything with magic that your other characters can’t do faster and for free with swords. Strago’s got her beat pretty hard.
Cyan only sucks if you let him. His most useful SwdTech is Dispatch, which you don’t need to charge. But if you use him right, you won’t need it. He’s as good a fighter as Sabin, and with a few esper bonuses he can do 80k without Atma or Illumina, if that’s the path you want to take.
I use Blitz, Tools, Throw, SwdTech, Morph, and Lore for almost the entire game, because most of them are free and they’re just plain stronger than any magic you have at the time. If you get Bum Rush as soon as it’s available, it’ll be doing 5000 damage when your best spells are stuck at around 1500. I’ve killed bosses in one hit with Chainsaw, and Shuriken cost like 30gp each. Character skills are disgustingly powerful, and if you say none of them are useful past the early stages of the game, it’s probably because you never really tried.
Locke has the one ability in the game I never, ever use, even once. I avoid wasting a character slot for him whenever I can. I’ll take him over Relm or Gau though… He can at least use the Valiant Knives.