Answer:
What is that which, though black itself, enlightens the world without burning?
What binds two people yet touches only one?
What has 4 legs in the morning, 2 legs in the evening and 3 legs in the night?
What is it that has four legs, one head, and a foot?
Held firmly in the hands, like a sword it cuts deep. Bloodless strokes, all, then forward we leap.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?