[MothEnthusiast]

I just had a friend grab a fist weapon and basic attack me in melee range with it on the test server. 2 procs of riposte happened, though strangely both happened after both hits of the fist weapon. (So it went fist, fist, riposte, riposte, instead of having the ripostes going between hits like with everything else.)

Edit: Give me a day or so and I'll run it through against just to be 100000% sure. Or someone else can, makes no difference to me.