Turn a switch on as soon as you get the item (or at the start of the game). Make a common event with a variable that tracks your step count. Check if there's a change. If there is, increase the characters HP.
-Instead of having the Player go through the Menu, you could have a Common Event always running and Checking
@>Control Variables: [0001:Steps] = Steps (You can find this in the "other" section of Control Variables).
@>Conditional Branch: [XXXX] is [XXXXX] Equipped
@>Conditional Branch: [0001:Steps] != [0002:Steps2]
@>Change HP [XXXX], + 2
@>
@>Branch End
@>Control Variables: [0002:Steps2] = [0001:Steps]
@>
@>Branch End