What is "unmighty"

Usage examples of "unmighty".

But as he followed up the chase, a mere thrall of the fleers turned on him and cast his spear, and it reached him whereas his hawberk was broken, and stood deep in, so that he fell to earth unmighty: and when his lords and chieftains drew about him, and cunning men strove to heal him, it was of no avail, and he knew that his soul was departing.