Every biome up to the plains had 2 armors (heavy and light), so my guess is blackmetal armor... or serpent scale armor which will require blackmetal.
As for other biomes, i have no clue for armors, but i hope there will be 2 in each.
For bosses i have only one guess. So far we met fenrings and crafted fenris armor, which are two similar words but different creatures. We still did not see fenris himself. In norse mythology fenris or fenrir is one of 3 Loki's children (Fenrir, Hel and Jörmungandr). And he is the most dangerous one who is foretold to kill Odin during the events of Ragnarok. Gods knew that so they captured him. At first he was kept in Asgard, but he kept growing at alarming rate so he was transported to a lonely and desolated place where he was chained to a rock by a special chains made by dwarves. My guess is that we will meet him as the boss of Deep North (lonely and desolated place).