While the game is not something I myself have played, I can likely break down that metaphor.
Basically, I suspect it is referring to a table, or a floor, or something shiny. (Basically, something you polish). And I suspect your confusion comes from the use of the word "brutal" in description, because brutality and polished things don't seem to connect.
Think of it this way, though - since you are in a barracks, that likely means military types. Lots of rules, lots of structure, and they like things perfect and hate to waste time on things. So the brutal efficiency of the polishing refers to the fact that this is something done extremely exactly, in the most efficient/quick way possible. It's done well, but lacking any sort of love or connection to the act - it is done because it must be so, and it must be done well, without wasting time or resources.