His weapon of choice is a morning star, attached to chain, which he can throw with ease.
Urobe, the oldest Viking in Halvar's crew, described Sven like this:
"Even as a young boy, he was very ferocious. He's very vicious and cunning, I can tell you that. And everyone hates him. If he sees something he wants, he takes it. And may god help you if you don't give it to him volunarily. You can't even count the number of villages he burned down. If you stand in his way he just strikes you dead. And then he plunders as much as he and his men can take"