The one with the tipper mechanic is Marth. Roy basically has negative tipper. He hits harder the more toward the hilt of the sword you hit with. In exchange for that Roy has pretty fast attacks.
So Roy has attacks almost as fast as melee characters but can't really bank on increased reach from his sword because he'll suffer in damage if he does. It's a classic tradeoff.
Chrom just straight up gets full damage no matter what. That's a problem.
Marth and Lucina are basically the same character. Marth has the tipper mechanic and deals more damage that way than Lucina but she doesn't suffer the damage fall off Marth does. So what Chrom should do is do less damage overall than Roy but more reliable damage than him.
His busted shit however is his up B. It gets out of combos for free, overpowers just about everything and for some reason you can drag people off the stage with it and Chrom dies second, despite it even looking like he should die first. That's just straight up bullshit. Bowser can't bowsercide anymore because that was considered overpowered but for some reason this fast as fuck sword character gets to have some fucking YOLO up B.
He should always die first.