No it likely wasnt attached to him:
He broke a carapace spur off his arm—a sharp and jagged weapon—and pointed it toward Kaladin. He had probably used one of those as a dagger when attacking Kaladin’s back.
The Fused are pretty crappy, but I would expect them to be able to walk and chew bubble gum at the same time. That is, they shouldnt have to move the weapon in order to turn their head every couple of seconds.