In 5x06, Hal used a knife in his fight against Tom. That knife isn’t the sort of thing that would just be lying around. It’s not a chef’s knife or a craft knife. It’s a weapon. So where did Hal get it from?
Maybe he picked it up somewhere between Honolulu Heights and that pub. (It’s possible he took it from someone, or stole it from somewhere.) The other alternative is that Hal had it with him when he left Honolulu Heights. But he left in a hurry, only taking the time to grab his coat on the way out of the door, so that would mean that he’d already been carrying the knife around with him. Which in turn would suggest that he was already getting to relapse.
Since I’m rewatching the season, I’ve just noticed that Hal used a similar knife when he was fighting against lady Catherine.
But Tom and Catherine are werewolves, so what about the burning blood?
Was Hal just being cocky or he didn’t realize about it?
I think it’s a combination of Hal being cocky, and also Hal never really planning to use the knife in the first place. Both scenes were primarily a game to Hal; the knife was mostly for show and to balance out the opposing party’s stake. He probably could inflict some damage without coming to serious harm himself if he wanted to/was careful, but I don’t think that was really the plan.
(No idea where he got that knife in 5x06 though.)