For a melee-based game this is a problem. See Barrow sets, 4 melee for 1 range and mage, that is a good balance. Current tier is 1 melee / range / mage, this is way too balanced. I would like to suggest adding 2 more melee sets and making the existing melee set more interesting.
Spear Set: Has high Crush Defense and Stab Attack on pieces(along with the Strength bonus). Set bonus: Increases spear damage by 15%.
Unarmed Set: Has highest Strength of the bunch, but mediocre defenses. Set effect: Increases unarmed damage by 200%.
Dwarven/Barbarian Armour Set: Has high Stab and Slash defenses, as well as the highest overall defenses of the bunch. It would also have a Crush bonus. Set Effect: Increases damage with Warhammers/Battleaxes by 25%. (battleaxes would also be improved 1 speed tier)
Partially solved by above suggestion and set effects such as; increases damage done by longbows by 15%.