Shiki vs Shirou: Too easy. Shirou sees Shiki treating a girl like shit, shoots him through the chest with a broken phantasm. Nuff said.
Arcueid Vs Shirou: Arc would be mad that she lost her boy toy, would immediately attack Shirou. Shirou, after having three vived dreams the past few nights(FSN, UBW, HF) would eventually find all the information of his dreams stored in his brain. He would counter Arc once, then again, faster and faster until he cuts her arm off with Caliburn. His mind is spinning with all the information of the servants; he next counters with Enkidu, then with Gae Bolg. A burst in mana erupts from Shirou, as he begins to believe in his fate. He wields duel Excalibers now, and rides on Pegasus. Arc finds her body being slowly eroded away by his might. She feels an emotion she has never felt before: pure fear. And she gives in. She lets her urges take control. She begins her Reality Marble. Suddenly Pegasus is dead, one of the Excalibers splintered to dust. But Shirou holds on. Grasping his chest, he feeds on the information past the boundary. And then, Ea. With it comes a mental flash through the life of Gilgamesh and the bitter words "You are the only one worthy to lend." Shirou lets out a battle cry, turns the world inside out, and transforms Ea into a bow. With the transformation the reality marble is struck and destroyed, with the echo of a million gongs. Shirou then transforms his remaining Excaliber into a broken phantasm, and lets loose at Arcueid. She ceases to existed.
Shirou is on his way to controlling the Will of the True Hero.