Daggers
I have an idea to make daggers useful: not a weapon of choice but something you might want added to an army. The idea is simple: dagger-like weapons normally have a low damage output and cannot retaliate, but have a large damage bonus against units who can no longer retaliate and ignore defense. Think of it as stabbing someone in the back. I am visualizing an assassin-type unit that is very vulnerable to attack. To compensate for this, he should be able to move 2 squares, attack once, and move 2 squares in a single turn to move in and escape from danger. Given that I suggested only 1 attack per turn, better make it a large damage bonus.
Weapons and Armor
To make weapons and armor feel more unique and add strategy to tactical combat, I suggest two things:
1. Each weapon has a bonus versus a certain armor type and a penalty against a different type.
2. Some weapon types have unique abilities that either process always or in certain situations.
E.g. If a long reaching weapon (spear) is used to attack a unit with a shorter range weapon (short sword), then the defending unit does not retaliate.
E.g. If a short range weapon (short sword) is used to attack a unit with a longer range weapon (spear), then the defending unit does damage first, or he gets a bonus to damage when he retaliates.
E.g. Blunt weapons have a chance to cause a concussion (stun), leading to the victim missing a turn, or not retaliating for a turn.
E.g. Cutting weapons have a chance to cause bleeding, resulting in the victim losing 20% weapon damage in HP per turn.
E.g. A certain weapon type can have the ability to retaliate forever.
E.g. Daggers ignore defense and get a large damage bonus against units that cannot retaliate, but can attack only once per turn.