Vi kan inte vara 100% säker på var han kommer ifrån, men det verkar otroligt troligt att han är Qohorik. Vi vet att Qohor är det enda stället att hävda att veta hur man arbetar Valyrian Steel.
The properties of Valyrian steel are well-known, and are the result of both folding iron many times to balance and remove impurities, and the use of spells—or at least arts we do not know—to give unnatural strength to the resulting steel. Those arts are now lost, though the smiths of Qohor claim to still know magics for reworking Valyrian steel without losing its strength or unsurpassed ability to hold an edge.
The World of Ice and Fire, Ancient History: Valyria’s Children
Vi vet också att det var Tobho som omarbetade is till Widows Wail and Oathkeeper och från ditt citat vet vi att han lärde sig det i Qohor.
"You have done good work, Master Mott," Lord Tywin told the armorer. "My steward will see to your payment. And remember, rubies for the scabbards."
A Storm of Swords, Tyrion IV
Och vi vet att han är väldigt bra på att lägga färg i metall, han har även lite röd i Valyrian stål.
"Nor I, my lord," said the armorer. "I confess, these colors were not what I intended, and I do not know that I could duplicate them. Your lord father had asked for the crimson of your House, and it was that color I set out to infuse into the metal. But Valyrian steel is stubborn. These old swords remember, it is said, and they do not change easily. I worked half a hundred spells and brightened the red time and time again, but always the color would darken, as if the blade was drinking the sun from it. And some folds would not take the red at all, as you can see. If my lords of Lannister are displeased, I will of course try again, as many times as you should require, but—"
A Storm of Swords, Tyrion IV
The Knight of Flowers bought all his armor here, Tobho boasted, and many high lords, the ones who knew fine steel, and even Lord Renly, the king's own brother. Perhaps the Hand had seen Lord Renly's new armor, the green plate with the golden antlers? No other armorer in the city could get that deep a green; he knew the secret of putting color in the steel itself, paint and enamel were the crutches of a journeyman.
A Game of Thrones, Eddard VI
Vi vet också att smeden i Qohor vet hur man lägger färg i stål så att bevisen tyder på att han definitivt utbildats i Qohor. Att se som han var en pojke när han tränade det verkar troligt att han är minst från de fria städerna eller åtminstone Essos.
Qohorik swords, knives, and armor are superior to even the best castle-forged steel of Westeros, and the city's smiths have perfected the art of infusing deep color into the metals of their work, producing armor and weaponry of lasting beauty.
The World of Ice and Fire, The Free Cities: Qohor
Slutligen hör vi att dessa hemligheter av Qohor är välbevakade så det verkar mycket osannolikt att de skulle ge dem till en utomstående, särskilt en pojke. Med allt detta tillsammans skulle jag säga att det är 99,99% säkert att han är Qohorik men med inget explicit citat kan jag inte säga säkert.
Only here, in all the world, has the art of reworking Valyrian steel been preserved, its secrets jealously guarded.
...
Maester Pol's treatise on Qohorik metalworking, written during several years of residence in the Free City, reveals just how jealously the secrets are guarded: He was thrice publicly whipped and cast out from the city for making too many inquiries. The final time, his hand was also removed following the allegation that he stole a Valyrian steel blade. According to Pol, the true reason for his final exile was his discovery of blood sacrifices—including the killing of slaves as young as infants—which the Qohorik smiths used in their efforts to produce a steel to equal that of the Freehold.
The World of Ice and Fire, The Free Cities: Qohor