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.
Ward of Air Gold Cost 0 Keywords Air Text
Before this Shugenja, or any Personality if this Shugenja is Air, is destroyed by a Battle action, you may destroy this Spell to negate it. Air Battle: Move this Shugenja home.
I know you need presence in battle to use abilities. But, let's say I've attached this spell on an Air Shugenja, can I still negate another personalities destruction even if the Air Shugenja is not present at the current battlefield?
Yes, traits aren't subject to the rules of Presence and Location and therefore Ward of Air's negation can be safely activated from home.