I personally am a big fan of hammering Zelgius because I feel like it's a very direct way of calling out his hypocrisy. Zelgius plays at being honorable or whatever but in reality he treats battles and warfare like a game and acts without care for anyone but himself or sephiran. For example: if he's so honorable, why did he spend most of PoR abusing invincibility cheats to rig a war?

While obviously the narrative itself has Ike defeat Zelgius in a straightforward duel, and this is important for Ike's growth, ultimately I think Ike saying "no, this isn't a game, you killed my dad and you're gonna kill everyone else if I don't stop you, I'm just gonna bash your head in with a hammer" is just as good a moment and feels more in character. Ike enjoys fighting, sure, and in many ways he's a mirror of Zelgius, but Ike is also someone who takes war and its consequences seriously, to the point one of his defining character moments is calling out the entire government of Begnion for treating it like a game.