Because unshakable has no performing personality, can it be used if you have no tacticians in a battle?
Unshakable and non-tacticians
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.
Because unshakable has no performing personality, can it be used if you have no tacticians in a battle?
No. See Tactical: A Tactical action that is not performed by any card can only be taken if one of your unbowed Tacticians is at the current battlefield.