I wish the trait trees were setup more like the following. Some basic stuff followed by some really cool ones:
Defender I/II/III = +5 defense/+10 defense/+15 defense
Endurance I/II/III = +1 hp per lvl/+1 hp per lvl/+1 hp per lvl
Resistance I/II/III = +5 resistance/+10 resistance gold/+15 resistance
Defender I + Endurance I unlocks = Leadership I/II/III = +2 to army size / +1 per level to army's defense / army gets +1 tactical movement and is immune to counterattack
Defender I + Resistance I unlocks Guardian I/II/III = +1 per level to army's dodge / army's dodge added to resistance for resistance checks / army takes -25% less damage and gets +1 defender
Endurance I + Resistance I unlocks Sentinel I/II/III = +2 tactical regeneration / 50% chance to stun any unit attacking Sentinel / +25% damage returned to attacker