Welly, well, well...

I didn't even notice that he was holding the sword oddly like that. Well, it appears as though it is a two-handed sword, thus it needs the support of two hands to hold it... being that he has his left hand in that position, I'm assuming it's to balance out the weight (I'd assume a sword made completely out of metal like that would weigh a decent amount). Well, he's not a warrior guy IRL, and he probably sits around his house all day playing DnD by himself, so I doubt he has any actual muscular development in those beefy arms of his (aside from what he gained by constant masturbation), so that probably would be the easiest way to hold it, as to balance the weight.

Either that, or that's just what naturally feels most comfortable.