I have been GMing (or judging if you use the vernacular from the rule book) a game of freebooters on the frontier, where 3 of my players have all chosen to become magic users. Each player has a focus which grants them some meager spell power allowing them to cast spells. Between the three they have 2 magic wands and an arcane orb. Each magic wand gives it's holder +1 spell power while the arcane orb gives it's holder +2 spell power. Now for a little while everyone was using everything as intended but at a certain point one of my magic users stole the arcane orb from its owner to get +1 power when casting a crucial spell. After this the players realized that the power gained from the magical focus could be stacked, and a single player could use every focus from the party to get +4 spell power and cast a very powerful spell. For a sense of scale each player has between 1 and 2 base spell power. To compound things the wands don't even have weight so for the magic-user already holding the arcane orb there is not even a weight penalty.
Now in principle I don't have any issue with this. If the characters pool all of their resources together they should be able to cast more powerful spells, however players have instead begun to perform a item shuffle each time they want to cast a spell that doesn't require immediate action, meaning that for the most part everyone just always casts very powerful spells. This I take issue with, because for one I feel like it starts to break the fiction and become more of a exploit and for two the players are just more powerful than I feel they ought to be at this stage in the game.
So this leads me to the question:
What can I do that will deter players from performing the item shuffle so frequently? I'd like to hand out reasonable consequences or costs for doing so while remaining in the fiction. For example one I like is telling the party that if they exchange items they are going to lose time (about 10 seconds or so), which in some cases is really valuable but in other cases is really inconsequential.