One-step, one-spell distance

The one-step, one-spell distance is a key concept in sword arts.

Background
The "one-step, one-spell distance" is a radius around a mage, approximately two to three paces, within which no mage can cast a conventional spell faster than an opponent can strike with a weapon. This concept coalesced after High Sorcerer Wilf Badderwell was killed in a fair duel by a nonmagical swordsman in 1132.

Note carefully that the one-step, one-spell distance is only an estimate and not a fixed distance: it varies between mages and from moment to moment, based on body size, speed, and even stance. Being better than one's opponent at gauging range, and thereby being better at timing when to switch between conventional spells and swordplay, can be a decisive factor in duels between mages.