To unlock Power (power attack) skill: train Strenght lvl5 and Agression lvl3. To unlock Speed(combo attack) skill:train Accuracy lvl5 and Agression lvl3. To unlock Focus(counter attack)skill: train Vigilance lvl3 and Concentration lvl5.
P.S. To the dev, this game is amazing, i've created really OP build that i reallt enjoy. Cant remember when was last time when i had so much fun with idle game :D Hope u will keep expanding it and making it more complex! Ty you dude, you rock!