I'd like to suggest adding 1 combat mechanic from Gloria Victis and 1 from Chivalry.
Kicks from GV: Special move you can perform at the cost of stamina. It deals very low dmg but it breaks the enemy's guard if connected. If you stop blocking just before it connects, you get no consequence. But if you are taken by surprise, you are dazed for 2-3 seconds, similar to the mercy mode.
Block endurance from Chivalry: you cannot spam blocks forever. You have blocking endurance based on blocking skill and str/con stat. If blocking durability is depleted you cannot use blocking move for some time, lets say 10 secs.
Kicks from GV: Special move you can perform at the cost of stamina. It deals very low dmg but it breaks the enemy's guard if connected. If you stop blocking just before it connects, you get no consequence. But if you are taken by surprise, you are dazed for 2-3 seconds, similar to the mercy mode.
Block endurance from Chivalry: you cannot spam blocks forever. You have blocking endurance based on blocking skill and str/con stat. If blocking durability is depleted you cannot use blocking move for some time, lets say 10 secs.