I have recently come across another source of info regarding steel making during the 1600's. Joseph Moxon put out a book in the later 1600's describing the design and use of lathes during the period. Mention is made of hardening and tempering steel. Not to be confused with case hardening, which is also mentioned. So it can safely be said a higher level of carbon steel was used in the 1600's for at least some springs, edged weapons tools etc.
It is also mentioned that the scimitars made of Damacus steel were better than the state of art swords of Europe. I am currently making a key for a crablock, and just bought Peter Ross's very nice video on making a crablock. He mentions that he had to use hi carbon steel for the spring. Close inspection reveals almost no movement of the spring as the lock is opened/ closed, just a bit of preload.