Terminator 4 salvation why was fight scene at the end so weak with the terminator 800 model and with no gun?

In terminator 1 the 800 went to right business with his machine gun when he tried to confront connor going for the immediate kill. Why did he in 4 decide to spend time tossing around john and going to confront him with no weapon? And how did johns shooting the pipes at the end send fire and ice on terminator but he himself didnt get sprayed by anything?