no cold is still weak when used for damage, people specially INT builds go for cold because:
1-snow shield gives almost 60% defense which is spectacular... most important skill for INT builds
2-INT builds have high magical defense and low physical defense so the ice guard is a must or STRs will own you without the snow shield
3-in pve or in pvp against builds with no immunity blues or cleric freezing is awesome
4-the last cold skills that increases physical defense permanently
light is your imbue and is the most important mastery for any INT build because parry ratio, speed, its nuke that is almost equivalent to the fire nuke and piercing force to increase attack and heavens force that increase parry ratio permanently.
if you want to be good at pvp then a weapon mastery is a must and since you use a spear maxing hesukal is a must
why a no go for fire ?
the fire nuke isn't that much stronger than the lightning one and same goes for the imbue, you also don't need magical defense since your an INT build and physical damage increase isn't that important
hope i helped
-Cross
i dont know whaat to do 
for all 3 classes