I suppose....with a sword such as this...a good indication of it's 'authenticity' is to actually 'wield' it, ..... if it feels 'right'.....and the price is right ....then I would definately take the risk.
I agree that the crossguard looks 'cumbersome', could it be that originally it had a knucklebow, which has been cut down / removed, perhaps due to damage. It might explain why it looks slightly 'odd'.