Flex vs. Hardness

I see a lot of people using these two concepts indistinguishably when in reality they are completely different.

Flex is how much a blade bends along its longitudinal axis. The amount of flex is primarily concern with the stiffness of the blade. Stiff blades will have little flex and vice versa.

Hardness is how much a blade deforms perpendicular to its plane. The major component here is the density of materials used and the construction of the blade. A lot of people associate hardness with the top ply but it’s not just that (more on that later). So, we can have stiff but soft blades, flexible but hard blades and everything in between.

But how does this influence how a blade plays? 🤔