As an upholsterer, my first thought was hog ringer pliers, also.
Upholsterers use these often when a Klinch-It Fastener can't
(normally) be used to attach coil springs to jute webbing, ie.,
awkward positioning, so an alternative tool (hog ringer) is used when
repairing springs/attachments without disassembling a whole piece of
furniture/fabric. We also use spring clip pliers, which is somewhat
similar to hog ringer pliers (but different jaws), to attach springs
to a stiff wire edgeing, for a framed set of coil springs. One can,
maybe, describe a spring clip as a modified/specialized hog ring,
though I doubt a spring clip can be used to ring a hog's nose. Hog
ringer pliers are a typical/common tool for attaching hog rings to
automotive fabrics in some nonvisible locations.
Yep, lots of uses for hog rings/pliers in applications other than