As a shield tech you will struggle to kill people if you go all def mods. I noticed this quickly and then looked at my power, crit, and surge stats. They were all at 0.
To fix this I bought the 50 PVP medic gun and implant that had power, surge, and crit.
You can also afford to swap out 1-2 accuracy/defense or accuracy/absorption mods for power, surge, and crit.
Do not touch the shield rating stat you want as close to 50% as possible. I recommend 47-49% sheilding and 40-45% absorption