"Master" is a bit of a baroque moniker. Can we agree that a "master" ought to be much further along than a "specialist?" i.e. the Java master should understand byte code and personally know folks of the original Sun Java team?
Otherwise it just sounds like I can become a Javascript Master in a few months.
I prefer the phrase "experienced in x". In my opinion specialist and master should have the same weight. Calling someone "specialist" can be a misnomer for a master if the scale for measurement is not agreed upon.
Otherwise it just sounds like I can become a Javascript Master in a few months.