david weaver
..kicking this stuff around lately, having seen Beach's test about s53 and then reading steve elliot's page discussing the necessity of diamond to sharpen it.

Looking at the composition:
iron 67%
Chromium: 10%
Cobalt: 14% (!!!)
Nickel: 5.5%
Molybdenum: 2%
Tungsten: 1%
Vanadium: 0.3%
Carbon: 0.21% (!!!)

Typical use: Landing gear, fasteners and driveshafts

Typical hardness in application: C54 (!!)

Cobalt, as far as i know, is added to steel to improve hot hardness. I haven't seen anything suggesting that it's great in hand tools.

I can't vouch for the interactions with V, but guess in small quantities, it's added to improve hardness, just as it is in O1.

Not much surprise with the rest, but what would lead someone to believe that this would make a fine blade steel?

It's my choice for the strangest blade, though I'm sure the quality is still better than shepherd's A2.