The non-critical second hit will not ignore shields.
Gives immunity to certain damage sources while grappling.
The second hit (critical) is slightly shorter than first one.
Trivia
Walking into a shop while equipped with the Tentacle and the Vorpan will trigger a special interaction with the shop merchant.
This interaction is a reference to the animated launch trailer, where at the end of the video the Beheaded and Guillain are using the Vorpan to cook a tentacle.