Well, I’m confused.
Although some things don’t add up, a few of the “confusing” things aren’t really “confusing” at all.
First, he doesn’t “know” the intruder but his name is “David” and he’s a “friend” was either what “intruder” told him or he said it that way as not to enrage the intruder. Either are perfectly reasonable explanations.
Secondly, They both did not have a hammer, but were likely struggling over the ONE hammer likely carried initially by PP for protection. Kind of like a half asleep husband that grabs a bat or pipe when they hear noises down stairs in the middle of the night.