Sure Erik's foolhardiness when attacking Halfdan the Black's and his crew convinced he's invisible is essentially funny. But the fact that he not only beats most of them on his own (do mostly to them all being shocked by his audacity). But he manages to inspire the rest of the Vikings to fight back as well. Turning the tide of a seemingly hopeless fight.
Halfdan: What's the matter, haven't you seen anybody fight before?
Crewman: No! There usually to scared of us.