Wights are a species of water creature.
These creatures are created by witches, and therefore have the same weaknesses as them. They are often created and used by witches as a means to guard a secret place.
Witches use their dark magic to create a wight, binding dead/drowned sailor's souls to a Wight's body in order for the Wight to stop decaying.
Instead, the body becomes bloated and strong.
They don't have eyes, since they have been eaten by fish, although Wights are known to have very keen hearing.
Because their creators are Witches, Wights have the same weaknesses as Witches. These include:
These three techniques are used, by Spooks to weaken and in some cases kill a witch or wight.
A victim may be totally unaware that a wight is near or lies in wait underneath the water. Therefore, the attack, when it comes, is swift and sudden. The wight "seizes its prey and drags it down into deep water, where the prey drowns while being slowly dismembered."
A wight was used to guard the Malkin Tower, which was located in Pendle. It guarded a secret tunnel, which led to the inside of the witch tower, but was later torn to pieces by a lamia witch.