I see this expression used in various political contexts; e.g.

Active defense means that... will play a waiting game and punch below its weight until the regime feels that it is ready to act more assertively.

I'm familiar with competing below your weight class in wrestling or boxing and I'm guessing that's the origin of the phrase; but does anyone know how it came to be used in this somewhat hacked form?

I thought it might be this
Hurd,
but I found other listings from '04, which is the year before this article was written.

sounds like a(n) eggcorn to me.

sounds like a(n) eggcorn to me. How so, Sweet Thing? [hug]

I figure it was once, "punch below its waist"?

<<hugs back>>

Mighty hoax from tiny eggcorn grows.