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 Fading Shadows is not an equip action, can they be attached to bowed personalities?
Fading Shadows You may include up to 10 copies of this card in your deck. Will only attach to a Ninja. After this card enters play: Lose 1 Honor. Battle: If this card is in your hand, choose your performing Ninja: Attach it to him.
Since Fading Shadows is not an equip action, can they be attached to bowed personalities?
Yes. The Battle action on Fading Shadows just requires you to choose your performing Ninja, with no mention of if said Ninja needs to be bowed or unbowed. The act of attaching itself also makes no reference of a need for the personality to be in a specific game state (other than in play, obviously).
You'll also note the Equip (Limited) Player ability doesn't specify bowed or unbowed either.