Spear Skill Set for Hero
Spears is the second best weapon Skill Set for the Hero. Thunder and Lightning Thrust are good attacks for Metal Slime enemies, assuming you don't have any points into Swords at all. Aside from the final ability, Lightning Storm there aren't many other very useful Spear abilities.
3 Points: +5 Attack while using spears
7 Points: Mercurial Thrust - Deals a little less damage than a regular attack but always strikes first in battle.
12 Points: Thunder Thrust - Only hits 50% of the time but when it does hit it deals a critical hit.
18 Points: +10 Attack while using spears
25 Points: Multithrust - Deals 50% the damage of a regular attack but hits 3 - 4 times.
34 Points: Critical Hit Chances Increased while using Spears
45 Points: Clean Sweep - Hits a whole group of enemies, damage decreases with each attack and the initial attack deals less damage than a regular attack. Not that good.
59 Points: Lightning Thrust - Replaces the Thunder Thrust ability.
77 Points: +25 Attack while using Spears
100 Points: Lightning Storm - A lightning attack that deals 190 - 220 base damage.