I'm trying to make the game more playable.
What to equip a lava sword need to have 6 strength , to take in 2 hands lava swords need 10 strength.
In order to open the upgrade goblins warriors need to build a tavern, and periodically go into it, at some point there will come a drunken girl, who will be the former commander of the emperor, she will help you with retraining from goblins-builders to goblins warriors. :)