if you look at what Sazed says about the religion of Trelagism, Trell had a brother, Nalt, whose eye was the sun, which he made brighter than all of Trell's eyes (the stars), perhaps this represent Metals. Nalt's "eye" is harmonium, being brighter than all of the other metals, which do not necessarily belong to Trell, but are not Harmonium.
So, considering this relationship it is Possible that Trell and Harmony are opposites, Just as Ruin and Preservation were.