Grapples have been powered down severely from the original rulebook. As any decent martial artist or police officer will tell you, a grapple hardly insures an armed opponent cannot do anything to you.
A successful grapple (Dex + Brawl, resisted with Dex + Dodge) does no damage. A grapple allows you bite an opponent, prevents him from kicking, using long arms (rifles, shotguns) or large melee weapons (swords, clubs). However, he can still attack you with pistols, daggers, his fangs, fists and the like. He cannot leave combat or run away while he is grappled. You cannot use weapons while grappling someone. You may let go of a grapple as a free action on your turn. To drag or move a grappled individual, you must spend an action dragging and wrestling with them (contest of Strength + Brawl, Diff 6, each success gives you one foot of movement, their successes cancel.)
You can break a grapple during combat by rolling Strength + Brawl, resisted with Strength + Brawl by the grappler. The grappled character wins on ties. You can also attempt to drag your grappler around as an action (contest of Strength + Brawl, diff 6, each success gives you one foot of movement, their successes cancel).
You may not grapple again the round after your grapple was broken by your opponent.