Ahh, interesting.
And yes, can well believe it'd be the resonance rather than the actual thing - weren't jousts by this point a little bit consciously old-fashioned? I base this thought on a throwaway comment by Caxton in a children's novel meticulous historical research, natch.
I am currently reading a really creepy romance where some men want to take revenge for women being raped, and swear to go and 'finger' the enemy's banner (the battle equivalent of a tournament favour) then ripe/rape (it's a pun) it to pieces, so the sleeve/sexual image thing was in my mind.
My mind is, on reflection, a bit twisted.