Here someone correctly said that not only skills are necessary but high quality stones too. it'is right.
I would add that nihonto knowledge is fundamental too.
If a polisher is poor in kantei, he will be poor in togi too... To polish means first of all to study the sword, his creator, his school. It means to to be excellent in kantei.
Unfortunally Ponzio till semptember 2017 demostrated was able neither to correctly read a torokusho and a nakago.
His cv is only selfmade, and honestly report nothing interesting.
Meanwhile Massimo Rossi is, on the other side first of all an estimated nihonto student who study tokens from 30+ years about. He was the only european to had ever partecipated to 3 different NBTHK togi contests, in 2009 (on suggestion by Yoshindo Yoshihara), 2010 and 2018... and to achieve 3 different nyusen. He polishes swords for Yoshindo Yoshihara here in Europe, and
collaborates with some european museums.
In may 2020 he had a slot in Japan Art Expo in Utrech to hold a conference on togi: https://japanartexpo.com/sword-related-presentation/ (event cancelled due covid pandemic).
...so please do not spend Rossi name near to Ponzio, they are white vs black, thanks.