A tool for swaging a fastener collar around a grooved fastener pin to secure two or more work pieces together includes an axially elongated anvil and collet that can slide back and forth to perform the swaging operation. Localized side areas of the anvil and collet are cut away to define a clearance space that can fit around projecting portions of the work that might otherwise obstruct the tool against proper placement of the anvil against the fastener collar. The anvil and collet are rotatable as a unit to enable the clearance space to be oriented at any desired location around the anvil circumference.