Quick responses

Perhaps he is just past his prime?

Well, nothing is explicitly stated which, in this poem, means it may as well not have happened, so I agree that it is a bit odd for him to not have tried anything. However, as I noted previously, others have tried to do something. I'm not familiar enough with the comitatus arrantements to know whether or not the leader was expected to lead his troops into battle, but I think the "past his prime bit" definitely fits here. We'll see that parallel again with the dragon.