Restoring vintage pens often involves the use of pliers, not one set but loads! There is a good deal of gripping, gentle twisting, bending and compressing involved, often in very confined spaces hence the variety. Pliers, and there is no singular term, are capable of exerting much more pressure than that applied by the hand. This is, after all, what they were designed to do but great care is needed when manipulating old, often brittle and delicate components. Never, ever, ever, use naked jaws of a pair of pliers on a barrel. cap, or section of a pen. Thousands of vintage pen sections have been ruined by careless use of these implements. As far as fountain pens are concerned they are very dangerous tools.
Particularly useful are 'needle nosed' and 'parallel jawed' pliers:
Section pliers are, probably, an essential piece of kit. If, after repeated gentle heating and trying to persuade a nib section to detach from the barrel by hand only it still will not budge then section pliers may well give the extra torque needed but, once more, great care should be exercised.
Forceps are, I suppose, pliers in essence. A set of long nosed forceps is very useful and so called, 'alligator forceps' are almost essential to a pen restorer. They were originally designed for removing foreign bodies and other medical procedures but may well have been designed for removing bits from a pen barrel.
Although pliers are very useful it should be reiterated that they are best left in the toolbox unless absolutely required and then treated with caution.