Roy features a "reverse tipper", as his sweet spot is at the base of his blade while the rest of his sword is weaker.

Does Roy have a tipper in Ultimate?

Roy has an attribute unique to him that other swordfighters do not have which is his inverse tipper; contrary to Marth specifically, his Binding Blade does the most damage if attacking near the sword's hilt, although it does weak damage and knockback when otherwise tippered.

Does Chrom have a tipper?

As mentioned above, the main difference between Chrom and Roy is that Chrom's attacks lack Roy's inverse tipper sweetspots, instead dealing consistent damage across the entire blade. ... Chrom's Counter deals less knockback against weaker attacks, but more knockback against stronger attacks.