IANAA. Wrestling has become a favored tactic of my PC’s from time to time. This is what I’ve used for my own sessions.
I assume this was to prioritize strike actions as the primary means of attack while maneuvers would be special or more theatrical. That said, it is very hard to pull them off and the mechanical advantages are not always worth it. My favored solution is to use the “heroic” house rules and remove the -4. If this isn’t enough then borrowing touch AC from 3.X or having a contested strength roll may be better.
The initial save happens with the attack. If pinned I do the save on the PC’s turn.
This is kind of muddled. The first time I used this mechanic I didn’t give the mobs any actions except to roll the paralysis save. After reading it again I think I was wrong. I think that a grappled character could still perform any action short of withdraw. While possibly more realistic, total action denial ended up being a little too powerful for me to believe it was an intended effect.
If you look at medieval fighting treatises, there are a lot of wrestling moves mixed in with combat, but they’re all very situational. If I wanted to guess at some rules:
anybody fighting unarmed, or fighting with a single weapon Fighting Style they’re proficient in (1H or 2H or pole), who rolls a natural 20 can choose a wrestling move to execute.
for more frequency, allow when rolling >= 20 including modifiers.
This gives strong warriors all the more reason to fight with a bastard sword, which makes my Fiore-loving heart glad. It adds a critical hit-type mechanic for players who find that exciting without directly ramping up the damage, makes fighter-types more dangerous but doesn’t add threat to unintelligent monsters.