I've never bothered to use Ewan without tower grinding, so I don't have a good basis for comparison. People say Elmer's hard to train in his join chapter, but he does like 10 damage to cavs, gets to like 50% crit with Emilia + Angelus support, can even start doubling with some speed levels/items, and he can take a hit on enemy phase. You don't even need to be particularly trainee-pilled to set up an occasional 3 kills a turn for him. Elmer's growths look like piss but he get so many levels that he still regularly sees a few green numbers before promotion on top of the nutty promotion gains (sage in AS is fucking +5 str.) He also has a distinct niche in the early to mid game as your only dark mage with natural bulk and good con. AS gives you many broken dark mages later on, but they're never going to be Elmer bulky and they don't have swords (axes if you're saucy and make him war monk) to play weapon triangle/bonk mages, or staves for support. He's just a solid generalist who fits well into any team composition, so I'm always surprised to see when even the devs are commonly like "erm, yeah. easily bottom 3 unit LMAO"