Mayalaran is the name with which Adolin's dead spren Shardblade identifies herself to him by tickling his mind, very faint, like a sigh. Upon learning this, he affectionately calls her Maya and invites her to bring down a thunderclast with him.
She is a blue one-edged blade. Her sharp side is sinuous, rippling like an eel curving up into a point. Her opposite side has delicate ridges, with the appearance of crystal formations. She is six feet long once summoned.
It is presumable that Maya might be able to be resurrected.
There are several indications in Oathbringer that Maya may be coming alive again; she attacked Adolin's enemy while she was a spren, has given her name, and seems to have taken less than ten heartbeats to summon as a Blade.