So, I am already a big fan of Keyan w/ VI, Collision Detector, E2, and Maul, but I am looking for a clarification as to how it works.

So, the obvious use: Keyan is not stressed, you use Maul to reroll, spend 1 stress to change eyes to hits.

The second use is the one I am more uncertain about:

Keyan is already stressed, so you spend the stress to change eyes to hits. Being unstressed now, he Mauls to reroll a blank. That's all good. But: can I then spend that stress as well, to change new eyes to hits?

Nvm, the FAQ states that his ability can only be used once per attack! Still strong, but not as strong, alas...

I would say only 1. It says " When attacking, you may remove 1 stress token to change all of your focus results to hit results." To me that means spend 1 other ships say "Spend A _____ to do _____." That allows them to be done multiple times, but that's just my thoughts. however if a second attack took place (gunner type, snap shot, etc.) I believe you would be able to again.