I think "skilled servants" is the closest you can get. They would not be as skilled as artisans or craftsmen, and of course your list already includes "artesãos."
I do agree that it's important to leave the Portuguese, but without a translation, footnote, or other explanation the reader is lost. So I would add the Portuguese in parentheses The following explanation shows that the meaning of the word has changed since medieval times, and certainly you are looking for the medieval meaning.

Here is the quote I found:
Mester (do latim ministeriu, "ofício de servo"). Ministério significava, no século XIII, o ofício do servo e aquele que prestava um serviço era o mesteiral ou ministro... O mesteiral tinha a sua arte (mester). Hoje, o mestre tem a sua arte mas o ministro tem muitas "artes"...



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Note added at 2004-04-19 22:41:03 (GMT)
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From WordNet:
I avoided \"craftsman\" because you already had \"artesãos.\" In English, \"craftsman\" and \"artisan\" appear to be virtually synonymous. Here are the definitions from WordNet:
craftsman:
[n] a skilled worker who practices some trade or handicraft
[n] a creator of great skill in the manual arts; \"the jewelry was made by internationally famous craftsmen\"
[n] a professional whose work is consistently of high quality; \"as an actor he was a consummate craftsman\"
vs.
artisan:
[n] a skilled worker who practices some trade or handicraft

The original meaning of \"minister\" is \"servant,\" as in the following #1 definition from Webster 1913:
1. A servant; a subordinate; an officer or assistant of
inferior rank; hence, an agent, an instrument.
Moses rose up, and his minister Joshua. --Ex. xxiv.