He was a little less than 10 meters from Knight Leader.
At that distance, each could attack the other in an instant, but Knight Leader did not move a step.
He sliced his dark red sword through empty air as if he were taking the situation lightly.
“!!”
A horizontal cutting attack came from a completely different angle and threatened to behead William.
When William bent over to dodge the attack, a number of flashes glittered in straight lines around him.
Immediately afterwards, Knight Leader moved his longsword like a baton and invisible cutting attacks rushed towards William from all directions. The undergrowth was sliced in straight lines, claw scratch-like cuts ran across thick tree trunks, leaves floating in the night sky were sliced in half one after another.

[...]

William used Ascalon to repel a “long range” strike approaching his temple from the side. A blade that looked like dark red rust only a few millimeters long struck the thin wire held on like a coping saw creating sparks and then pierced into a nearby tree trunk.

“It is a fragment of the sword.” Knight Leader easily revealed the trick that he should have kept hidden and continued swinging around his sword. “The fragments of some excellent weapons and spiritual items still display the power of the original. For instance, the sword used by King Charlemagne had the fragment of a sacred spear inside it.”

Toaru Majutsu no Index vol.18 ch.5 pt.5