so yea im here to tell u about the PvP engineer....
if ur going PvP engineer ur gonna want to focus on the human form and not the mech form....meaning u want to lvl the skills that deal single target dmg such as "heavy artillery" and "brain drain"
at later lvls u might also want to put some lvls in ur own personal minion that explodes itself to deal dmg to ur enemies (it also reduces their pierce resistance by 20%)
for certificates u want to focus on crits and crit-dmg as well as the engineers ACC certificate
(myself i use hunters crit dmg, hunters LCK, engineers crit rate, engineers ACC, blade dancers crit rate and a malice decreasing certificate)
knowledge points i recommend starting with maxing the atk-speed and ACC (7 points in each) and then go for crit rate and crit dmg (which u should not bring over 15 coz they cost 3points for each lvl above that)
and that's pretty much all u need....after that when they increase the cap lvl u can do whatever u want and with ur engineer but i see these ase the basics for PvP engineers