Oh, try and find either sword of the samurai i think it is called (can make high quality katanas or nodachis and other asian themed weapons) or medieval weapons recipe book.

Tempered weapons are like the premium tier stuff, need a high temperature welding kit to repair it though and carbon steel. ( tip if you can't find a welding blanket you can get the materials for a makeshift one from deconstructing two of the oven parts from deconstructing an oven)

I think the carbonisation process needs a book though.

You can sometimes find genuine weapons and armour in mansions ( i personally find proper maces of the weapons that are genuine) but yeah reading the descriptions can save you from a bad situation yeah