Colin Farmer in Chorley, Lancashire was taken to a nearby hospital to be checked over by medics, but he was discharged shortly afterwards, BBC News reports.
The 61-year-old, who is now looking to pursue legal action against Lancashire Police, recalled: "It felt like I was grabbing an electricity pylon."
Police were cautious when encountering Farmer as there were reports of a man armed with a samurai sword in the area who was determined dangerous.
Farmer, however, was headed to a pub when the incident happened on Friday evening (October 12).
A police spokesman stated: "We have clearly put this man through a traumatic experience and we are extremely sorry for that.
"We have launched an urgent investigation to understand what lessons can be learned."
The actual man the police were looking for was later apprehended for being drunk and disorderly.
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