A nifty thing to have would be “offset” modules. They would be only found after battle like “broken module” or “broken high-performance weapon” but be usable.
They would be like modified weapons that could be equipped on to different ships. One example would be beam cannons that could be equipped on interceptors or assault railguns that could be equipped on frigates. The damage values would of course be tweaked but I think it would be really cool to have the occasional weapon module that can be equipped on a different ship. Like Engine Overcharge that could be equipped on frigates.
The downside to these could be that they are only usable on one certain rank, or a smaller spread of ranks like 5-7 instead of 4-8.