I’m sorry, I should have explained better.
Aermet 100, AF1410, Premomet and Ferrium M54 are the strongest and toughest steels In existence today (or they where maybe 10 years ago). This steels are even tougher than any Maraging steel and that 4140/4340 steel, and they can be hardened as well (54-56hrc maybe). They make S7 look brittle. Can they be used to make a knife/sword? I’m sure they can. But they usually only can be found in rounds and are not for the average heat treater. For one to get those amazing properties these alloys have to offer, they must be forged to shape and heat treated with precise temperatures. Maybe mild steel can be even tougher, but it’s almost like rubber, it has almost zero strength.