John in NM
The one thing I remember clearly is that the stress/strain moduli do not change (in general at least) with different heat treatments - O1 has the same modulus of elasticity regardless of heat treat, ie it takes the same force to deflect it. It's brittleness is modified by the heat treatment however.

Whether this extends to PM materials I don't know, but I would expect it to do so. The PM steel may seem "weaker" because it breaks, but what does that matter? Same force applied to produce a broken blade or a severely bent one, who cares? Either way you have a ruined blade!