I reckon the "cuts on his arms" is a furphy (fabrication for USA readers).
As I posted previously, if there were cuts, how did they occur?
Did one of the victims get the knife off him, attack him a few times, only to have the accused wrestle the knife back again?
Or, if he cut himself during the attack, how did he cut BOTH arms?
Cuts to one I can believe, if he held the knife in his right hand and accidentally hit his left arm in the attack.
But cuts to BOTH forearms?????
Nup, can't come up with a reasonable scenario for how that would have happened.