To level your armour skill, you need to use it in combat, thats fine and works!
But its linked to your current weapon, and without leveling multiple types (Which shouldent really happen tbh) you cant level your armourskill past a fairly low amount!
I suggest un-linking it or changing it to level with a higher XP gain, so its not left at half if not less than your highest weapon level, or let it continue to gain XP based on mobs, rather than your weapon. But limit it to the highest weapon level you currently have
EG - Level 25 blaster, highest armour skill possible is 25, But if Onehanded = 40, then armour skill could = 40?