I disagree, morris, with the blank slate assessment.
It is possible that Harry is a fine thrall laid over a weapon- or that the weapon is a fine thrall slumbering inside of Harry. It would use the Chekov's gun on fine thralls.
But I rather lean towards the whole choice side of the series being that Justin may have intended to forge a weapon, but Harry's nature was resistant- so what resulted is someone with high endurance for slugfests, high pain tolerance, and an absolute knowledge/lack of hesitation to "go for the throat" if needed- but not a berserker.
Harry does have pretty classic PTSD after Susan/what the Red Court did to him.
I think it's either a rhetorical device- see how far he's been pushed!?- for tension, or an excuse for the whole Darth Harry/Mirror Mirror universe. It also maybe will come up as why he has Soulfire/is employed/an agent of an archangel- even if that archangel is the archangel of vengeance. He keeps making the same choice to not become warped.