Unpredictable, you see. Never know what he's going to do next. Probably doesn't know himself half the time but that is the joy of it. So small, physically a boy among men but an abundance of heart and glorious imagination.
Running back after kicking his first international points on a debut against Italy last month Thomas asked the Welsh captain for an opinion about his shorts. "Do they look all right?" he asked. "That's Arwel for you," Jonathan Humphreys said.
Wary of silver linings, the Welsh nation know better than to get carried away by an honourable defeat at Twickenham but in Thomas and Robert Howley and the team's ambition generally there is real hope for the future.
In any case there was a smile on the face of the Welsh coach, Kevin Bowring, who is clearly a man with some sense of tradition. Too many mistakes for his satisfaction but some joy from impertinence. "We don't want to stifle flair," he said.
Whether that embraced the move that led to Wales taking an early lead, Thomas electing to take a quick penalty rather than kick for goal, is another matter. However, it was a trick to light up an era of pragmatic northern hemisphere rugby.
Just something that came instinctively to Thomas's mind, his team-mates no less puzzled momentarily than the opposition? If so, we can stand plenty more of it. Welsh breath was held while Thomas twirled in sudden panic before passing left for the move that led to Hemi Taylor going over.
Moments like that can be heart stopping for coaches and supporters alike but Bowring knows that the policy he is advancing must accommodate them. If the intention is positive, errors of judgement are forgiveable. A rampant Scotland at Cardiff in two weeks' time? "Can't wait for the team to be out there with a Welsh crowd behind us," Bowring added. "I think we showed today that there is a lot to build on and that we are moving in the right direction."
A popular theory was that England's greater power would be too much for Wales in the second half and it clearly irritated Jack Rowell that they were unable to maintain momentum when ahead by 13 points. Theirs is a team heavy with introspection. The muscular efficiency that brought domination in Europe or the more expansive game that Rowell claims to be seeking?
Trouble is that there are members of his team, Will Carling included, who convey the impression that their objectives are beyond the public's comprehension. They should pay some attention to the dissatisfaction that has grown up among England's supporters. Significantly, Twickenham on Saturday was almost devoid of atmosphere.
Who is running the show anyway? Is it all too democratic? "The players run some of our training sessions," Rowell said when under interrogation. Caught off camera towards the end of the match when Wales were coming back strongly, Rowell was heard to say that he could not believe what he was seeing. What he saw was England hanging on grimly.
A converted try would have brought Wales a great victory and out of the effort they put in came another example of Thomas's thrilling audacity. Spinning clear he darted after a deft little punt with the outside of his right foot that might have made something out of nothing.
You cannot teach things like that. They are in the genes. As Jimmy Murphy once said of George Best, the only thing you ask of Arwel Thomas is have you got a brother? For the sake of rugby it is to hoped that Wales persevere with him.Reuse content