My players and I often have a bit of conflict or frustration in our games because one player in particular is quite controlling, and feels that they can have their character just snatch up what they want because they said they wanted to.
This isn't a form of "Instant Actioning" I feel I should be able to control. The player waits for me to finish, but interrupts the other players before they can pick up what they deserved, and often undertakes actions that weren't discussed. Since they are on the same level, I don't feel I should have the power to intervene in their play. It is their game as well and I don't believe in overruling their choices as it is their place, not mine. I'll only ever say "no" If it breaks the rules.
For example, we had this scenario where my players were in forest that was blanketed by spider webbing. They overthrew the spider inhabitants and decided to cut down one of the cocooned bodies hanging from the roof. I reward their thorough and clever searching by stating (After they cut open the webbed body) the body was that of a Dragonborn local hero in the area who wore a mask that improved his breath attack. The mask was designed for one of my Dragonborn players specifically because he is new to the game and rarely gets a chance to assert himself in battle over the other more experienced players, so I wanted him to feel like a more valuable asset. Before he or any of the others had a chance to pick it up, the controlling player snatched it up and refused to give it back (Even though she had no use for it). Nobody wants to stir things up by trying to assert themselves over it and usually just forget about it and move on. Regardless it happens quite frequently, even though there is more than enough loot to go around for everyone.
I don't want to cause meta by being this outside voice that tells her to give it to someone who deserves it. I also don't feel like I can address her personally outside of games because she doesn't take these kinds of discussions well.
The excuse is usually "My character is Chaotic, that's what they do." I have emphasized in the past that having the Chaotic alignment doesn't necessarily entail that kind of playstyle. But it fails to go heeded.
For the sake of making the game better for everyone, I'm looking for an ethical solution to ensure everyone is having a good time and that it isn't spoiled by one player trying to take control. Obviously subtle punishment that discourages snatching is an option, but is it unethical?