Gripping the Dussack
Like the longsword, there are several ways to grip the dussack.
The Sabre Grip
The most common grip shown in the illustrations is a sabre style grip for the dussack. In this grip the weapon is held comfortably in the hand with the fingers clasping the haft. The thumb, however lays down the spine of the haft either directly on it (at the 12 o'clock position, or just on the corner of the weapon (at around the 10 to 11 o'clock position). This is roughly the same as the sabre grips seen in Hutton or, in the second case, Waite.
This position is used for cuts and thrusts (it's particularly effective for these) as well as for crooked cuts (krumphauw).
The image below shows the sabre grip on the dussack.
The Hammer Grip
The hammer grip clutches the hilt with the whole hand as if gripping a hammer. The hammer grip provides great strength in the gripping action, and is excellent for movements where the angle between blade and arm is quite small, however as the blade is tipped forward it causes the wrist to bend at an awkward angle making it both ineffective and dangerous for cutting or thrusting in the extended position.