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.
Engage: Raise Ujirou's Force, and the Force of a target Personality in his army, to equal the Force of a target enemy card.
If Daidoji Ujirou Engages at a battlefield facing a 2F Kensai Equipped with two +2F Weapons (total 6F) does Ujirou raise his Force to 6F?
If Daidoji Ujirou Engages at a battlefield facing a 2F Kensai Equipped with two +2F Weapons (total 6F) does Ujirou raise his Force to 6F?
I'm sorry, but I can't quite follow your question.
D. Ujirou's ability doesn't target "Force". It targets a Personality in his army and an enemy card, then it raises the first target's Force (and Ujirou's) to equal the second target's.
Now, nowhere does it say "printed" at all, let alone in conjunction with any mention of "Force", so I hope it helps when I say that at no time does the ability ever assess any card's Force other than its current Force in relation to any other Force. If that doesn't help, perhaps try to ask again with more specifics and perhaps some hypothetical examples.
EDIT: Sorry, but I can't tell when you edit your questions without looking at the thread again, and if it's already been replied to, it's unlikely anyone will do so and notice the fact. By "ask again", I meant posting a follow-up thread. But, by chance, I did notice this one and the answer is:
If Ujirou targets the Personality in your example, he would indeed raise his Force to 6.