Never understood why Gambino was pissed that Guts was practicing his swordsmanship. Gambino himself stated that Guts would have to earn his keep soon in their mercenary group. That should make him happy if anything lol
I always thought he was just annoyed Guts was letting his sword training get in the way of other chores. There's also the possibility of Gambino not liking the idea of Guts catching up to him, but I doubt it.
Gambino's behaviour is bizarre. At times he seems to look out for Guts.. giving him medicine for his wounds, saving his life in combat.. but then he shows pure hatred for Guts by selling him to Donovan, slashing his nose in practice, etc. Is he bipolar?
Gambino is also pissed off that Shisu died even though he never gave two fucks about her when she was alive. I think he's just possessive, liking to have things but not really enjoying them. Guts was bringing some good money on fights and gave him a chance to be a bit of a father, but ultimately it didn't compensate him losing his wife and his leg.