Well, consider that we are playing a game. I did not post this in "Realism Discussion" for a reason. I've heard that the foot slot is the last thing most people heirloom, if they bother to heirloom it at all. Legs already take such little damage that it doesn't seem needed. An incentive like this would definitely make them worth it, especially to high strength builds. Everyone's afraid of the running archer being made faster, but this would benefit low agility builds more.
Based on other stat changes to heirlooms, just 1 or
maybe 2 Athletics is all that would be needed.
Still you dont run faster, you only feel more comfortable while running.
That completely depends on the shoe that's being modified.