Hello All, for this achievement you simply have to get 10 kills with secondary weapons in a round. I personally used the M1911 pistol because it has decent damage and not too bad of a rate of fire. Rotterdam or Devastation will probably be your best bet due to more close quarter combat situations but if you are playing conquest, many of the maps are long enough (~30 minutes) so it can really be done on any map.
I did this on Devastation and stayed near flag C by the church. usually enemies (and your teammates) will group up around here so it is easier to pick people off. Also, I believe "Assist counts as a kill" will work towards this achievement (please correct me if I am wrong) because I was counting in my head during the match and got two kills this way.
This is my first guide so I hope this helps!