Great question!

There are two forms of this kind of manuver:

Bashing Attack - This is where the attacker uses his body weight to ram an opponent with the intention of knocking him down. If he uses a shield he gets a +1 Attack Level. However, this attack does 1/2 damage. The opponent adds their Strength Bonus to their AC. So weaklings are more easily bashed (due to negative Strength Bonus). Why do it? Because once the opponent is on the ground attacks will have a +1 Attack Level, and no counter attacks are allowed. To stand up requires that the opponent not get hit in the following melee(s). Example: Arik's group won the Initiative so Arik attacks first. He uses his shield to Bash Attack Bob. Arik's AL = 1 +1 for shield = 2. Bob is a large guy with +1 Strength Bonus, and he's wearing Leather and a Shield (AC: 2) so Bob's AC total = 3. Arik has a 2:3 and needs a 5 or better on the roll. He rolls 5. Bob goes down. Bob, now down, can not counter attack, and took 1d6 damage (rolled a 3). Divide by two and round up (as per normal math). So Bob took two points of damage and can not counter attack. Next Melee Arik loses the Initiative. Bob's move is to stand up, and can not attack this melee. Arik attacks with a +1 AL because he is in a commanding position over Bob. He hits and does 3 damage with his attack. Bob can not stand up. Next melee. Bob wins Initiative again. He stands up. Arik Attacks, but misses this time. Now Bob is standing, but can not counter attack. Next Melee... return to normal combat.

Full Strength Blow - This kind of blow uses the full body weight of the attacker to add damage to a blow. It does +1 Damage, but has a -1 Attack Level. IF Fatigue rules are in effect (optional) then the Full Strength Blow takes double Fatigue Points than a normal blow.

Parenthetically, there is a Precision Blow which does the opposite of the Full Strength Blow, but has the added attribute that it gives a +3 on the second Critical Hit Check roll and allows the Character to target the specific area of the critical. Example: Arik tries a Precision Blow against Bob's right hand to disable him. He gets a +1 AL, and -1 Damage for the attack. He rolls a 6 on the attack which allows him to check for Critical Hit. Normally you need to roll a 6 on this roll for it to be a Critical Hit. Because the Precision Blow he gets a +3 on that roll. However, if he does not score the critical hit then the entire attack fails and no damage is delivered at all.

Thoughts/Opinions?