This Keyblade is a Dark Keyblade wielded by two Keyblade Masters: Toru Marek and his successor Morrigana.
A Keyblade that enhances Magic and defensive capabilities while still retaining speed, it is discovered that Toru's (unknown) Old Keyblade was sacrificed to create this Keyblade, it may be the same Keyblade shape however it is fully a Keyblade of Darkness now.
It may be possible that the Keyblade Rain Storm had been Toru's original Keyblade, much like Gaia Bane was the Keyblade used by Blaid before he used too much Darkness and hence damaged the Keyblade.
Toru's Keyblade however, has one paticular ability that seems to draw everyone's attention, it can allow Toru to have flashes into the future as well as strengthens his Sensual sight.
After Toru was killed, he asked that his Keyblade be given to one of his apprentices: Morrigana, since then Morrigana has taken Toru's place in Masterhood and trained the Apprentice: Zalel, Zalel later took on her "Grand Master"'s duty of training new recruits in his place.
Uses under Toru
When Toru weilded the weapon he was able to use it to grant a form of second sight to himself.