Raitei wrote:yes, tracing costs mana. even for shirou, who is just transforming a part of his body ( his body is made out of swords ), it still costs mana.
however, when he fully activates ubw, I don't think he need to spend anymore all swords are there, and he just take it from there without spending more.
also, body reinforcement is not wholly impossible for him. it's not such complicated as reinforcing other living creatures, you know ( like caster did ). maybe a bit higher than object reinforcement. heck, even when he activates his circuits, his parameter is slightly boosted.
I would like to disagree with the statement on UBW. Even after UBW is activated, the user needs to supply some magical energy to maintain the reality marble, even though magical energy to create swords is not required. There is that talk about how a light destroyed an already disappearing reality marble at the end of UBW. The only thing that can explain it is that Shirou was running out of magical energy and as a result, the reality marble was disappearing. And the game also says how too much of Rin's magical energy was used by Shirou without asking her, which wouldn't make any sense if it was a one time thing. He wasn't projecting anything, so, it couldn't have been because the image got fuzzy in his mind, which, if was the case, would mean he wouldn't have been able to corner Gil anyways. So, it has to cost some magical energy to maintain the reality marble, maybe not that huge, but significant when the magus is a novice, such as Shirou.
I agree with the rest.