This is something that requires explanation if you are not familiar with rules light Sword & Sorcery games like Barbarians of Lemuria and especially when all you ever played is d20 games. I couldn’t see how the choice of system makes a difference either until I really started to learn some other games as well.
GM: While you are sitting at your table in the tavern, an officer of the guard and two guardsmen approach you. The officer steps next to your chair and orders you to come with him to the palace.
Player: Is the officer within 5 feet of me so I can strike him?
GM: Yes, he is right next to your chair, looking down at you.
Player: Is he wearing a helm?
Player: What kind of helm?
GM: It’s a type of steel cap.
Player: How close are the two guardsmen? Am I in the area they threaten to make Attacks of Opportunity?
GM: They are too far away to attack you from where they stand.
Player: Okay, I want to take my mug and bash the officer in the head with it to knock him out.
GM: Make a Sleight of Hand skill check to see if you can grab your mug without drawing suspicion.
GM: The officer has a 15 on his Spot check and notices you reaching for the mug. Roll Initiative.
Player: I got a 15.
GM: The officer has a 9, the two guardsmen have a 17 and a 6. The first guard is too far away to see what is going on so you go first.
Player: I try to hit his head with my mug.
GM: Are you still sitting or do you stand up first?
Player: Can I still draw my sword in the same round when I stand up and make an attack?
GM: No, standing up and drawing a weapon are both Move Actions. But since your Base Attack Bonus is +1 or higher you could draw the weapon while you are standing up as a single Move Action.
Player: Okay, so I try to hit the officer with my mug while still sitting, then stand up and draw my sword at the same time.
GM: Since the officer has not had a turn in this fight yet he can not make an Attack of Opportunity because you use an improvised weapon. Do you have a special ability that allows you to make attacks with improvised weapons without a penalty for not being proficient with it?
GM: Okay, then make an attack roll with a -4 penalty for using an improvised weapon and a -2 penalty for sitting.
Other Player: Is there even enough light in this smoky tavern to make a normal attack roll or should the attack have a 20% miss chance from Concealment?
GM: They are standing right next to each other, I think that’s good enough to not have a miss chance.
Player: My attack roll is 12.
GM: Since the officer has no weapon in his hand he can not parry. But as he is still flat-footed he also loses his Dexterity bonus and Dodge bonus to his Dodge Defense, reducing it to 10. You hit him. The mug deals 1d3 points of nonlethal damage plus your Strength modifier.
Player: Since he is flat-footed I also get my extra 1d6 Sneak Attack damage, right?
Player: Okay, that’s 1d3+3+1d6… 9!
GM: Since you said you specifically want to bash him in the head, I only apply the Damage Reduction for the helm, but not the armor he is wearing. So that’s 8 points of nonlethal damage.
Player: Does that knock him out?
GM: No. As it is his turn now he draws his sword and makes an attack against you.
Player: Oh well, was a fun idea though.