Back in 3e, E.N. Publishing released a book called "Four Color to Fantasy," a superpowers add on for 3rd edition. One of the sample characters we presented was Zidi Wheatling, the halfling titan. The artist's inside joke was that she illustrated 3'4" Zidi wielding Cloud's sword from FF7 as her primary weapon, and Tidus's watery bastard sword as her off-hand weapon.
But she was a superhero, so it was okay.
In my games, if a player wants to do something that normal people simply cannot possibly accomplish physically, like wield a pair of greatswords as if they were escrima sticks, then we just decide, "Okay, your character has some inherent magical powers that let you pull this off." I run a pretty flexible style setting, so if a player wants to be superhuman, it's fine with me.
If, however, the majority of the group prefers more clear delineation between what is magical (wizards, warlocks) and what is mundane (fighters, rangers), and if the group believes there can be no such thing as a magical warrior, then for the sake of the rest of the group's enjoyment, the player who wanted to be a super-strong warrior should change his character idea.
For me, though, I see no problem with magical warriors, even if the Rules as Written says they have a 'martial' power source as opposed to a 'magical' one.