The Ichwan Bedwine are powerful fighters, with the ability to attack swiftly, and cause mental anguish on their opponents. Some say they have the ability to control their opponent's minds, and command them to do their bidding. Being descended from the ancient Earth tribes of bedouin wanderers, the fremen also have many meditative self healing powers. They have a deep seated tribal sense of group power, and their fighting skill would seem to be enhanced when they combine to take out their enemies.
If you wish to become one of their brethren, then you must find one who is able to introduce you to their ways, and sponsor you into their fold. Please feel free to ask any of the higher level fremen online about the guild, although please do not ask any of the wizard fremen, as they really can't help you in this way.