Reading some of these comments is getting a little exhausting.
Erdrick would no doubt be representing the abilities of DQ's "Hero Class", a class that he actually started within the series himself. Sure, he's a magic swordsman, but that doesn't mean he'd play anything like Robin. Even if a character's concept sounds similar to another one on paper, that doesn't actually mean they'd play anything alike. If that were the case, Captain Falcon should just be "Speedy Mario" since they're both punchy-kicky fighters with fire effects on some of their attacks. Obviously, that isn't the case. Basically, it's the execution of the concept that matters, and Erdrick's spells wouldn't even behave like Robin's anyway.
Erdrick's Wiki Page can show you all the different weapons and spells he could use in his original game.
Here's the page for the "Hero Class" in general so you can see what else they could potentially pull from.
Erdrick has loads of potential to be an interesting and fun character to work with. There's so many different directions you could take his moveset. Heck, if they had it so Erdrick could equip different weapons on the fly, that'd make for an extremely unique character that could change how their normal attacks work in order to adapt to different opponents. Maybe you stick with the balanced sword, maybe you switch to a lance for longer range, maybe you switch to a chain sickle for more speed, etc.
There's so much you could do, and it really only takes a little bit of creativity to come up with some wild stuff.
