Definition of "powerless"

In Sweden, as we saw, the mistletoe which is gathered on Midsummer Eve is attached to the ceiling of the house, the horse's stall or the cow's crib, in the belief that this renders the Troll powerless to injure man and beast.

1890, James George Frazer, The Golden Bough, volume 2, page 362

It is said that his right arm had grown powerless from having been raised so often over the heads of those whom he baptized.

1914, James Joyce, A Portrait of the Artist as a Young Man