besagew
A small disc of metal which protects the armpit, a piece of armor typically worn together with a spaulder or pauldron; a rondel, sometimes especially when used to steady a lance.
The decorative richness of the armor is enhanced at the pauldrons, besagew, elbows, and tassets by rosettes in relief, radiating channels, and embossed foliage; the last motif appears also on the hinged cheekpieces of the armet, […]
Where it comes from
From Middle English besagew, besague, besagu, from Old French besague, whence also besague (“double-edged axe or war-hammer”).
Adapted from the Wiktionary entry besagew (CC BY-SA 4.0).