We are digging into this way too much. If Rey offers Ben the lightsaber, he could accept it or refuse it. Either way would have the same meaning: that he has been redeemed, and is either worthy or Rey is worthy.
I disagree. I think redemption should not be so easy. Just say you’re sorry for the death of millions, and you get your lightsaber back as if nothing has happened. In my view Ben Solo should take responsibility for his actions, if he lives.