[Valatar]

You can build and buy armor with elemental resistances on it. But does it confer any sort of penalty? Is the armor weaker against the opposing element or anything of that sort?

[Saigan]

Yes- you will incur all the bonuses and penalties of that element when wearing the armor. Say for example you have fire element armor. This will protect you against fire spells, the higher % the more protection. However you will take MORE damage from an Ice element attack, again- the more % the more damage.

It may be prudent to save some armors with high elemental %s for cwertain areas with enemies you have a difficult time with.

Example: those little hopping b#stards in the Relics site are light element, as is the miniboss and there are no dark element creatures in that area making Light element armor a good choice.