Pretty simple question, and its possible I'm just missing something. The rulebook lists Pilum and Frankish throwing axes as being impact weapons, however when I look at the Merovingian Frank lists, I don't see any UGs with Impact weapon, is there a Frank list with Impact weapons?

Fransiscas are not treated as impact weapons.  That seems to be a definition inherited from DBM that has been overlooked during proof-reading. 
We have treated Franks and similar as Devastating Charger, Short Spear

Richard