Double blessing can work - in fact, I think it's fairly viable with Jotuns. Niefelheim though - can't remember if they still get the Jotun Woodsmen, and the Niefel giants are pretty expensive to build a strategy around (especially as they're capitol only, as are the Woodsmen). When you go so heavy on a bless strategy, it doesn't make sense to build all that many non-blessed troops....
And if your troops were routing frequently, it doesn't sound like you centered it around the woodsmen / Niefels, since once blessed they wouldn't have routed. (You _were_ blessing them, right?
)
Also, Earth Momma doesn't go particularly well with Jotunheim, imo - her fatigue climbs _way_ too fast, since she isn't comfortable in the cold. Personally, I think Nature/Water works better with Jotunheim; possibly Nature/Fire, or Nature/Air (protection from all those nasty crossbows).
Better luck to you in the future.