Trow, to believe.
Twi-bill, an axe with a double-edged blade. It was the weapon which Odin carried when he appeared to men.
Unbitted, never taught to obey the bit, not broken in.
Unholpen, unhelped. Holpen is the old form of the p.p. helped.
Unstable, changeable, not lasting.
Uttermost horn, the signal for Ragnarok. It was believed that Heimdall, one of the gods who guarded a bridge called Bifrost between Asgard and the earth, would blow a blast on his horn which would be the sign for the beginning of the great battle between the gods and the powers of evil.
Venom, poison.
Wall-nook, an opening or bend in a wall.
Wallow, to roll about upon the ground, e.g. "Fafnir, the wallower on the gold."
Wan, pale, pinched with suffering.