Ah-ha! "In a Mirror, Darkly" (Part I)?
Arrrrrrrrrrgh. I really tried very hard to find one from that episode that wouldn't be easily identified.
Chalk it up to me having seen that episode so darn many times! I think that's about when Archer is picking up the 23rd century phaser, no?
It will be a couple of hours before I can get a screencap up. Sorry for the delay!