A sword is not used in many traditions but today water witches use one as a ceremonial option instead of a athame or wand in some parts and instead of a broom in handfasting and some other gateway rituals.
Traditionally a witch would not have had a sword, but as a living religion we have the right to modify it as we feel appropriate.
It will not surprise you I am sure to find that we call our kings and coven swords exclaimers, after the power sword given my Merlin to king Arthur of round table fame.
In many of our covens we have role that we give the name of merlin to, the historic merlin not being a single person but a number of people over a long time using the same title. Their main role within the coven is in the organization of training in craft skills, however when a queen, king or high king witch is present they go in front of them carrying a sword. Many of our senior members have their own swords, and some covens have them as well.
A trip around antique shops that specialize in military items will show a wide range of historic swords, but in addition reproduction swords are available from collectors shops, including a variety of Excalibur's.
From a beginners viewpoint a sword is not required and many covens do not have one until an occasion arises when they would like to have one of their own.
It is cleansed and consecrated in the same way as the athame.