In the Team Fortress 2 console, type:

achievement_unlock TF_MEDIC_ACHIEVE_PROGRESS1
achievement_unlock TF_MEDIC_ACHIEVE_PROGRESS2
achievement_unlock TF_MEDIC_ACHIEVE_PROGRESS3

This will give you all three new weapons, without ruining your stats by giving you all the new achievements as well.

I don't know why VALVe left this in the game, I assume it's an error. Profit before it's patched!

 

Medic!