If you are 22, and I assume you have the level 20 pet, then your pet should only double attack. Our pets can't dual wield until 29 I believe. Either way, your pet should be showing pretty much any weapon you put in it's hands.
Did it just start doing it out of the blue, or have you not seen a weapon on your pet since level 1? I'm not sure if there is any options to turn such graphics on or off, and that would be my only guess off the top of my head.