It took place between 5.15am-5.45am yesterday (Monday) when two male suspects forced entry to the premises.
A male member of staff was alerted after the alarm went off.
When he went down to the bar he was threatened before the suspects made off with a number of items.
The suspects are described as white British males, in their 20s, about 5ft 10" tall wearing grey fleece tracksuits and trainers.
The stab wound was described as "minor" but required hospital treatment.
Detective Constable Jason Mohan of Calderdale CID said: "Clearly this has been a distressing incident for the victim, and I would appeal to anyone who was in the area at the time of the robbery, or who has any information that may help identify those responsible to come forward. Enquiries are ongoing."
Anyone with any information is asked to contact DC Mohan at Calderdale CID via 101 quoting 13170001375. Information can also be passed anonymously to the independent crime fighting charity Crimestoppers on 0800 555 111.