A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
A player, 18 September 2012
Furumaro (relevant text) Reaction: Before an action destroys Furumaro: Negate his destruction.
Daigotsu Eiya non-xp (relevant text) After Eiya enters play: Lose 3 Honor. All duels involving Eiya destroy the duel's loser.
Flame and Lightning Limited: Choose your performing unbowed Personality and target another player's Personality: Your Personality duels the target. Permanently remove all abilities and traits from the duel's loser.
Assume I play F&L using Eiya targeting Furumaro (on my turn) - and win the duel
Do I get to choose the sequence of effects so as to remove his Reaction ability first, then destroy him (in such a way that the the ability can't be used)?
Brook Cunningham (rules official), 19 September 2012
Furumaro (relevant text) Reaction: Before an action destroys Furumaro: Negate his destruction.
Daigotsu Eiya non-xp (relevant text) After Eiya enters play: Lose 3 Honor. All duels involving Eiya destroy the duel's loser.
Flame and Lightning Limited: Choose your performing unbowed Personality and target another player's Personality: Your Personality duels the target. Permanently remove all abilities and traits from the duel's loser.
Assume I play F&L using Eiya targeting Furumaro (on my turn) - and win the duel
Do I get to choose the sequence of effects so as to remove his Reaction ability first, then destroy him (in such a way that the the ability can't be used)?
Upon looking at Daigotsu Eiya, it was decided his trait could use some more modernizing for clarity. So, it now looks a lot more like Kakita Ichigiku's.
Now, this does mean that you don't get to choose the order, because the implication from "additional" in Ichigiku's and (now) Eiya's trait is that the destruction occurs after the duel's normal consequences for losing. However, this does work out the way you want (if you're not Furumaro's controller ), in that Furumaro's ability would indeed be removed before he could use it to save himself.