I'm not super component at 5e yet, but that seems like an artifact of unimaginable power in all versions of D&D.
I think his plan was to give it to one of the players with hopefully most of the charges used up. It was a costly item because it had the protection from magic missiles as well as the spell protection from arrows on it and he added protection from rays. I thought it was overpowered and said so at the time. But he took it as sour grapes on my part. I know I would not have a magic item like that in my game.
Though reading all this and reading some of the comments I do wonder if in hind sight he was trying to provide a counterpoint to the bow. Not just the magical aspects but I was a ranger and it was my major weapon. Not to totally screw me over there was no way he could have known that I would I almost fall into a chasm and lose almost everything except my bow and a few arrows from another PC. I really flubbed that save. You know to make it hard for me to take the guy out easily. But I will never know at this point and it was eight years ago.
I do know that DMs can screw with a PC if they are having issues with them and I think he had been unhappy with me because the session before I had totally misunderstood something and that caused a screw up he had planned for another player.