[Baalz]

Vanheim and Eriu have a lot of the same notes, but the melody is very different. The strength of Vanheim is in it's troops, the strength of Eriu is in it's commanders. Dual blessed Vanheim sacreds are among the very best units in the game, while none of Eriu's troops are better than passable. On the flip side Vanheim's commanders lack nature magic which is a critical component. Without nature you lose
barkskin - your protection is now 14 instead of 21. BIG difference as now your average spear wielder has a good chance of causing damage.
resist elements/poison - many, many counters now open up

Also, the E/N bless required for commander blessing is completely different from the classic W/F bless which most benefits the sacred units.

Eriu and Vanheim play completely differently, there is no way one can carry out the strategies of the other.