I really do wish there was a bit more research done into tool making in general and blacksmithing in particular. Not to mention metallurgy.
There's amazing online resources available and plenty of videos aimed specifically at authors for fantasy works explaining the basics of early renaissance weapons, armour and tools. Tod's workshop, schola gladiatoria, skallagrim, etc etc.
All of the objects he makes were forged, not cast. Cast material doesn't take hardening and tempering. Cast iron is relatively new material with very high carbon content, so much that it's essentially iron carbide. Wrought iron is what would have been used for everyday objects, which has no carbon in it-- this you make by simple burning off all impurities during smelting by getting it as hot as you can. That doesn't temper or harden either. Steel-making is a delicate and complicated process where you need to get just the right amount of carbon. This was often done by folding organic material into the iron together with flux and cooking it off. The best historical steels were close to what we today call "mild steel", but they had lots of impurities compared to modern materials.
All of that is something I learnt after a few hours of research for a story I was writing, so I can say first hand that it doesn't take much to get at least some details right, it is a story about smithing after all....