Its a basic Heavy Attack/ Life steal / Slash with high status but in Xatu's hands, it does have some additional benefits.

1) Shield Generation. Xatu's defence is their ability to evade attacks. but when they get hit, it can be hard. The daggers ability to get shields allows another layer of defence

2) mind haze reduces detection to 10 m from 15m, or just 2m shorter than Grasps of Loks firing range. Get closer without being detected.

3) the Blight effect helps with energy management, movement ability (stacks with his 4th), and adds viral damage.

As Grasp of Loks is good at targeting and destroying weaker foes, this dagger will be used for harder ones. The heavy attack will force proc Slash, open then up to front finishers, proc life steal and [Regen] shields.

The two empty slots are for your choice.