It's not the highest priority, but it's also not the hardest thing: the verbiage used around turrets can be quite a bit clearer.
Current word choices get the general idea across, but they're very "quirky:"
"Turret slot" is a bit awkward. Turrets don't go "into" anything, they get attached to something. The normal aeronautical term for this is "hardpoint" and that's used in a lot of other games. If subsystems can add cargo space, it feels natural that they can add hardpoints, too, and it feels right that big guns could span multiple hardpoints. "Slot" may as well be "thingy," as it's not conveying anything physical or precise about what's going on.
The words for describing kinds of turrets can be simplified:
"Weapon:" instead of "armed," which is ambiguous (as armed can just mean "active" or "ready"), or "combat," which isn't bad but struggles in having a good comparison word ("non-combat turret" is wordy), describing what the turret is simplifies things. If a turret's main job is to blow things up, it's a weapon.
"Tool:" we have both "unarmed" and "civil" in different places right now. Neither of these is ideal in conveying what's intended--"unarmed" can just mean "unavailable" or "inactive" while "civil" is outright unclear. Like before, describing what it is helps: if its main job is to harvest, fix, or move things, it's a tool.
"Universal:" the word "arbitrary" carries some very specific connotation of something being random, capricious, and/or meaningless. That's not what we really want here semantically; the idea is that you can mount anything to this hardpoint and "universal" captures that well. "Flexible," "multi-purpose," and a lot of other things can work, too, though I prefer the simplicity of "universal."
"Countermeasure:" I don't have a big beef with "defense," but this might be more precise.
This could all feed into some very slick and elegant UI changes (like having a clearer demarcation of hardpoint types and availability in the ship menu), but the naming is a very quick way to tighten things up.