Heavier instruments for toenails: wide-jaw clippers, strong nippers and files that survive a thick nail. Same steel and the same hand-set edges as the manicure line, sized for the load.
Why a fingernail instrument fails on a toenail
A toenail is several times deeper than a fingernail and much less forgiving. An ordinary clipper has a narrow curved jaw and a short lever: meet a thick nail with it and the jaws spread under load before they close, so the plate is crushed and folded rather than cut. Buying a sharper version of the same shape does not fix it.
What to look for
A straight jaw fifteen millimetres or wider, so it crosses the nail in fewer bites and does not curve into the corner. A long handle, because cutting force comes from leverage rather than sharpness. And blades that close along their whole length — hold the instrument to a window and shut it slowly; daylight at the ends is where a thick nail will tear.
Nipper or clipper
For a genuinely thick nail, a nipper — plier-shaped, two handles, a spring — beats a lever clipper. It delivers several times the force and lets you see the cutting line, which a clipper hides under its own body. A heavy clipper with a wide straight jaw is the easier instrument to hold and enough for a nail that is firm but not extreme. The method matters as much as the tool: how to cut thick toenails without splitting them.
For older hands
Where grip strength or reach is the limit, the instrument matters more, not less: long handles and a spring that opens the jaws on its own reduce the work to a squeeze. This is the case where paying for a forged instrument is most obviously worth it — the effort saved is felt every time.
An ingrown edge is a different problem
It is caused by how the nail was cut, not by the nail being hard, and cutting deeper into the corner makes it worse rather than better. What each of the specialised instruments actually does — and where the line is between care and a job for a podiatrist — is set out in ingrown toenail tools.