Walker felt like his heart was under pressure. Just looking at what was happening while he imagined how the metals and the manas were moving was hard enough. But the stress he was under as he tried to manipulate these manas was more than his body was used to.
The weight of stress from making other manas lacking in one spot was something his body screamed to fight against,. It was not the natural flow but it was also not harming the world. It was just different by many times over from what he had always done. How he had manipulated mana in the past.
Therefore, when he felt that the metal had been pulled from the spatial flames and that they had died down, Walker did not immediately find the strength to use the all around appraisal. Walker watched as the wandering blacksmith stared at the super hot ingot of metal that had just dropped right before them. It was not perfectly shaped and he feared to touch it and ruin the current settling of the metal.
Creation is hard, cheer me up!