What does being a master do??
 

what does it mean to be a master with an apprentice while playing?

When your apprentice spends money on NPC (buy stones, armours, skill etc) he master gets 10% of what they spent.

In the mean time, an apprentice with a master will receive in game rewards at lvl 10, 20, 30 and 40.

The master/apprentice system was bugged up for a while and the master wasn't geting the 10%.. I'm not sure if they've fixed the bug yet.