the.com/besague

means A besague is a medieval polearm or staff weapon, sometimes described as a kind of two-pointed or double-bladed implement carried by foot soldiers.

from The word is French, and beyond that the trail goes cold — it's one of those antique arms terms whose precise form and meaning blurred over the centuries until lexicographers themselves disagree. It may be related to the family of bisaiguë / besaiguë, meaning roughly 'twice-pointed' or 'two-edged' (from a sense of 'doubled' plus the root for 'sharp,' the same aig- that sharpens aigu and acute), which would fit a tool or weapon with points at both ends. But the honest answer is that the besague is so rare and so old that its etymology, like the weapon itself, has largely been lost.