Craig Stewart, 32, from Devon, was treated at hospitals in England but had no movement in his left arm.
After three years of treatment at Morriston Hospital, he can move his previously paralysed arm.
Surgeons from the Welsh centre for burns and plastic surgery have spent 12 years developing pioneering treatment.
Following the accident, which happened soon after he left the Army, Mr Stewart was treated at hospitals in Devon and London.
"My arm was just like a dead weight. I had no control over it. It would just hang down by my side," he said.
Mr Stewart was then referred to specialist consultant plastic surgeon Dean Boyce in Morriston, who took muscle from his thigh to act as a bicep.
After a further year of physiotherapy and hydrotherapy, he was able to bend his arm.
Two months ago, a tendon was switched from his wrist to his hand, allowing him to have limited movement in his fingers.
The fork lift driver said: "It happened and I had to live with it. But starting to get everything working again is great - it's a bonus."
Morriston is one of the few places in the UK that can treat injuries to the brachial plexus - the network of nerves in the neck that control upper limb movement.
Mr Boyce called it "a very complex area of surgery".
An ex-serviceman who severed his arm in a car accident 10 years ago can move his fingers again following pioneering surgery at a Swansea hospital.