I think it is incredibly important at this juncture to point out that as soon as the player sold the armor, the way they discovered that the other two items were gone was that they went "Now we're going to sell the gauntlet and ring."
The players didn't "forget" that they bundled them together. They didn't expect them to be sold, because the player was just selling the armor. They were good natured and played along, but that doesn't mean that the DM was in the right. So, I don't understand this line of logic at all. The players didn't forget about the existence of the items, they didn't realize that by saying they were selling the armor that they would end up selling the things that they packaged along with the armor.
Let me ask you this. Let's say you are playing D&D, and you find some 500 gp diamonds and five spell scrolls slipped through a magic ring, and you say you bundle it together. Then, you say you sell the spell scrolls. The DM describes the merchant as saying "All of it?" And, you're like "Yeah, all of it." Then you go off in game and say you're going to identify the ring, and the DM says "Oh no, you just sold the ring."
Are you absolutely sure you would be okay with this? 100% sure you wouldn't be even a bit teed off at the DM for that?
They are two completely unrelated items, so no I wouldn't expect that would occur nor would I be happy with it.
Actually, the DM in question is assuming that when the player says set of armor, they also mean things that aren't actually part of the set of armor. So, how do you reconcile that?
With the rules. PHB pg 145
Chain Mail...the suit includes gauntlets.
Plate...a suit of plate includes gauntlets.
You can't purchase a set of gauntlets separately in the game, and in the game they are expected to be part of a suit of armor. Even historically for plate armor, the gauntlets would have been made with and for that suit. And in this specific scenario, the DM even pointed out that they did not look like the original gauntlets made for that suit. They are still part of the suit, just not oem.
If there had been some discussion about the gauntlets at any point prior to selling the armor, that probably would have made a difference to me as a DM as well. But it would appear that there was no point, until after the sale, that the indicated any specific interest in the gauntlets alone.
If a player said "I'm selling the car" and then later mentioned that he was putting on a jacket, and the DM said "oh no, the jacket was in the car you sold" would you consider that fair? I'd consider that unnecessarily antagonistic personally.
Just because something is stored with something else does not make it that thing. The gauntlet and ring are not the suit of armor. They were just bundled together, like putting your jacket in the back seat of your car.
But this goes beyond being stored with something else. It's part of it. Reasonably and as noted in the rules. The DM wasn't trying to set up a scenario where they would be fleeced, it presented itself naturally and he (as the NPC) took advantage of it.
That doesn't mean that I don't think it's unreasonable to not consider them part of a suit of armor. If, as DM, that's the direction you'd go with it, that's fine.
Does that mean the new suit of armor they purchased also didn't come with gauntlets? Because I think that if they aren't part of the suit when you sell them, they shouldn't be when you purchase them either.
But if I was the player in this scenario I might have initially been annoyed (like for a split-second, then in character), but then you look at how it played out, and how gauntlets are handled in the game, I'd be fine with it. It's an "I can't believe I did that" moment, like the jacket in the back of the car, leaving your wallet or briefcase on top of the car, your lunch sitting on the kitchen table, or the concert tickets in the drawer. We do boneheaded things and they become funny stories for the future.
It's extremely difficult to handle an interaction like this where an NPC is trying to get something of value from the PCs in a negotiation. Because you can't describe every single thing that they can see, it's automatically assumed that if you mention something it's important. Which is why I make sure to put in a lot of descriptions and such that aren't important. But mentioning the gauntlets at any point in this scenario would virtually eliminate the possibility that smith would be able to succeed in duping the PCs.
I totally understand why some people would be bothered by it. I just think that based on the description, the game concept of armor, and the importance (or lack thereof) of what they lost it's a non-issue. If something is really an issue for my players, then we'll discuss it and make a decision. If that means retconning something, so be it. But this wouldn't have been one of them in 35+ years.
Ilbranteloth