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.
Since attaching an item is an action, does attaching peasant armor (-2 chi item) to a 2 chi personality trigger Udo's ability (the personality was destroyed by the armor)?
Udo reads:
Maho Reaction: After the resolution of an action that destroyed a Follower or Personality: Create a 2F/2C/0PH Shadowlands • Undead Personality at Udo's location.
Since attaching an item is an action, does attaching peasant armor (-2 chi item) to a 2 chi personality trigger Udo's ability (the personality was destroyed by the armor)?
No.
Effects come from where the effects are printed in ink (http://rules.l5r.com/CE_Effects#Source_of_effects). In this case, that means the item is the source of the -2C.