Hard stepping irons is when you make club shafts stiffer. It is in the reverse order of soft stepping. The pitching wedge shaft would be moved to the 9-iron head with the 9-iron head being switched over to the 8-iron head and so forth.
Doing this would leave the pitching wedge without a shaft so you would have to buy one after hard stepping. The 3-iron’s shaft would be surplus.
The effect of hard stepping helps the shafts become a little stiffer while lowering ball flight after contact. The club lengths will become longer after hard stepping.
If you wished to keep the original shaft length, you will have to make changes to the shaft’s butt end.