Following an obvious line of thought, I had a look at the verb "to wage" as in to wage war. There is according to the OED an etymological connection with the noun being discussed and also a link to a use of the word wager that I had not encountered previously: "wager of battle". Meaning an ancient form of trial by combat between the parties or their champions; I'm aware of the practise (Arthur's knights were always at it), but haven't come across that expression.

The links with payment for work are shown as being through medieval English and French, but seem quite obscure to me. Can anyone please help with a better explanation?

dxb.