Well, I don't know if you are looking for heavy custom abilities (triggers), or just custom abilities using warcraft templates, or HERO or UNITS abilities... But here is my 0,01 cent to your request:
- Life Steal (Least);
- Bladestorm (Deals damage to all enemies nearby);
- Berserker (Increase attack speed);
- Spear (Piercing Related):
- Faerie Fire (Active armor reduction);
- Corruption (Passive armor reduction on attacks)
- Vorpal Blades (Piercing attack that also hit targets behind the primary target);
- Firebolt (Active that deals damage and stuns the target)
- Shadow Strike (Active, that throws an envenomed spear, dealing damage and slowing);
- Increased base attack range, if melee or ranged;
- Critical Strike;
- Envenomed Weapons (Passive poison);
- Trueshot Aura (Passive damage bonus, for itself or for the group);
- Bash;
- Firebolt (With melee cast range, that stuns and deals damage);
- Evasion;
- Increased base attack speed;
- Life Steal (Greater);
- Shockwave (Cutting wave that deals damage);
- High Damage, Slow attack speed;
- Finger of Death (Melee cast range, deals a lot of damage);
- Drunken Brawler (Passive evasion AND critical);
- Orb of Slow (Passively has a chance to slow target);
- Chain Lightning (Chakram bounces on targets, dealing damage);
- Bouncing Attack (Ranged, If Chakram is thrown);
- Fast attack speed;
In my project, I have a Swordmaster, a Spearmaster, a Ranger and a Sentinel. Maybe they can give you some ideas.
This is everything I could remember/think for now.