Grognak's axe (Fallout 4)

Grognak's axe is a unique weapon found $$

Gameplay
Hits from this weapon cause more stagger and targets take bleed damage. It also has a hidden effect of less AP cost in V.A.T.S. (standard medium speed weapon, e.g. a Chinese officer sword, gets ~3 swings at 7 Agility, Grognak's axe gets roughly twice that).

Location
Inside Hubris Comics, in an Advanced-locked display case behind the front desk. The display case can also be unlocked by a nearby Advanced-locked terminal.