A 61-year-old blind man Tasered in the back by police who thought his stick was a samurai sword has been offered an undisclosed sum by Lancashire police after it admitted using excessive force.

It is understood to be the first case involving a Taser where a police force has admitted using unreasonable use of force and accepted that the officer did not conduct an adequate risk assessment before discharging the weapon.

The 61-year-old stroke victim, who cannot be named for legal reasons, was walking to meet friends at his local pub in Chorley in 2012 when a police officer mistook his white cane for a sword. Officers had earlier received a report of a man in the town centre waving a large sword.

The police officer discharged his stun gun from behind, into the victim’s back, and then knelt on the man’s back and handcuffed him as he lay on the ground.

CS Stuart Williams said at the time that the officer in question had not been suspended but the force deeply regretted the error.

The victim brought a claim against Lancashire constabulary for false imprisonment, assault and battery and breach of his human rights under the 1998 act. Legal action against the force was settled on Thursday for an undisclosed sum, subject to court approval, the Guardian has learned.

“Lancashire constabulary has accepted that it was a highly regrettable incident which should not have happened,” solicitor Sophie Khan said, adding that the sum paid to the victim took into account aggravating factors including his age and disability. “It should be reconsidered whether the use Tasers is adding to the effectiveness of policing at all, when it just causes grief.”

In July, an independent inquiry was launched to look into the use of stun guns by police in England and Wales after an inquest verdict linked their use to the death of Jordan Begley, a 23-year-old factory worker, in Manchester.

Home Office figures show the police used stun guns on 10,062 occasions in 2014, a fall of 3% compared with 2013, the first year that use of the weapon has not increased since their introduction seven years ago.