Safety shears
Blunt-tipped shears of the kind paramedics use to cut clothing, kept within reach during rope bondage so rope can be cut quickly in an emergency.
Safety shears, also called trauma, EMT or paramedic shears, have angled blades and a broad blunt tip that slides along skin, which is why emergency staff use them to cut clothing off injured people (Wikipedia; Shibari Notes). Rope educators treat them as essential equipment. Liverpool and Merseyside Peer Rope calls a cutting tool the most important item in a rope kit, says never to tie without one, and warns against knives because of the risk of injuring the tied person; Anatomie Studio mentions fainting or a fire alarm as reasons to cut. Shay Tiziano of Twisted Windows recommends practicing with them in advance. Shibari Notes adds two caveats: cutting is often not the safest way to release someone in suspension, and the common belief that shears are single-use has no documented basis it could find.