Zhang Tie's thought, although sounded unrealistic came from his real experience and gnosis.
Do you remember that battle puppets hall in the underground Bloody Sacrifice Hieron?
During the period when Zhang Tie stayed there, Zhang Tie purposefully activated those battle puppets time and time again to improve his battle skills. As a result, in that precarious lobby, Zhang Tie's battle skills gained a surging momentum in a short period; especially his "Fiery-dragon Spear Skill".
As for a knight or a fighter, actual combat was always the very shortcut to improve battle skills and power. If a knight wanted to test his battle strength and sharpen his battle skills, he'd better have actual combats with others knights.