Described by the Tinkers' Construct mod itself, "The Cleaver is a heavy defensive weapon. It has powerful strikes, but is difficult to wield." The Cleaver, when held, will give infinite Mining Fatigue III until unequipped and as such has a lower swing rate than other weapons.
The Cleaver is an advanced weapon from the Tinkers' Construct mod and as such requires the Tool Forge in order to be crafted, rather than the Tool Station. It is composed of a large sword blade, large plate, and two tough tool rods.