There will never be any of the 'arrow-timer' or 'laser-timer' ridiculousness in the Rumbles dictionary. Arrow-timer only crops up once in a while and is absolutely silly sounding, and I've never even SEEN laser-timer used before.

The ONLY reason we use 'bullet-timer' as a short-hand for 'has the reflexes to react to bullets after they've been fired' is because it's a phrase that picked up some kind of use OUTSIDE of Rumbles thanks to the awful Matrix movies.

Use 'FTL reflexes' or whathaveyou, and 'Catches arrows' or 'reacts to arrows'.