Hydraulic Busbar Cutter (8" Straight Blade) Bus Bar Cutting Tool M-200Q

I have nothing against it, but the disappointment came when I cut off a couple of dozen parts from mild steel. And the knife turned out to be blunt. I removed the phase on the knife and welded on the carbon edge and hardened it. And only then he began to cut perfectly. The question is to the manufacturer, is it really impossible for such a price that this product costs, to make a solid knife out of hard steel? Make inferences.