Feniurme
I'm happy with the direction and development you've had in mind author, frankly there are fanfic authors who don't bother to understand the source material and get so many mistakes in world building or combat. Just a question why did you make the mc trace his own arm for reinforcement magecraft. Reinforcement is a universal skill that mages can use to fortify themselves the "tracing" part is unique to Emiya because of his magecraft Gradiation Air. He doesn't need to "trace" his own body technically for it to work. You can see Rin and Luvia spar with each other using reinforcement without "tracing" because they can't use that in the first place. Same with Kairi (Mordred's master) in apocrypha he reinforced a book to block an attack without "tracing". Anyway keep up the amazing work I'm excited for the fights when the mc reaches Orario
You have so many opportunities now that you have chosen such a versatile power like UBW. I would recommend you to tweak its abilities a bit to make them your own. For instance, you could give him the ability to control his projection telekinetically more efficiently than Shirou, and have his weapon spin while being controlled to create slash damage instead of only piercing damage. You could also consider giving him the ability to fight with telekinesis, like Alucard's distant sword-fighting techniques from Castlevania