I'm replacing 1 of my trinkets with Heroic Light of the Cosmos. The thing is, im not sure which one to replace. I'm currently spec'd Arcane. The trinkets I have is Relic of Yu'lon and Essence of Terror (normal). They are both upgraded fully (2/2).
Which trinket is superior? Which one should I replace.
EDIT: I'm going for Mastery build (NOT haste)
Also, if I decide to change spec in the future for whatever reason, which trinket combo is best for Frost and/or Fire?