Not sure why this just popped into my head but here's the idea:
Accuracy Correctors that work on Defense. Requirement: BR instead of boost.
Since we always want offense to be better than defense what limits does it need?
Just a starting point perhaps:
Experimental Evasion System. Requirements: BR action.
When defending, during the "Modify Attack Dice" step, you may perform a free BR action to cancel all of your dice results. Then, you may add 1 evade and 1 focus result to your roll.
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BR keeps it from being on every ship (and probably some ships that would need this). It almost certainly locks you into the focus action (since you want that for end results and can't BR 2x a turn).
What slot should this take up and what should it cost? Other requirements or ideas?