|"That's not what happened at all!"
This topic is considered non-canon because it never appeared in the TV series.
The Constrictai Double-Headed Axe is a weapon favored by Skalidor. It is a dark brown ax with a large, black, double-bladed head and a large point on the opposite end (alternately, it is a dark brown Spear with black ax blades on the opposite end). Some newer versions of this weapon have a slight variation, where the bottom of the spear is flat instead of rounded.
Apparently, the ax is only wielded by Skalidor himself, whose great strength presumably allows him to use it to devastating effect.