I think a pistol rework is needed for sure, for me the off hand pistol is reasonable but it can be polished, I would like to see really concrete changes in the main hand pistol. As a condition weapon or power weapon has no potential like they are now, they should focus either on condition only or power only (my preference is power, and improve the holosmith sword with a little more bleeding and also burning) on main hand or so making a hybrid weapon that really works, including a better cast time cause pistol is a one handed weapon but is currently slow as a two handed weapon. Core engineer has just a few weapon options, we don't have weapon swap, and kits that should be additional weapon options don't work properly.
Another very requested and important change that the engineer needs is surely in the turrets, there are good ideas being discussed about them in other threads, devs just have to make minor balance adjustments and work on them to make it happen.
In my opinion we also need to improve the grenade kit, bomb kit and mortar kit by making them more interesting and useful, such as the flamethrower, elixir gun and toolkit style, when you have physical/condition damage associated with useful combat utilities like pull, block, knock back, fields, finishers, jumps and so on, maybe ammo system on bombs or one cast with 2-3 chain explosions (such as pulses, slightly increasing the cooldown), delayed-explosion grenades that attach onto targets hit (like the underwater weapon skill Timed Charge with a medium aoe radius explosion) and mortar with homing projectiles (like underwater weapon auto-attack Homing Torpedo, large aoe radius explosion as well) plus minor side effects on those kits (changes only aplied to skills 2-5). Some changes in that direction would make these two kits more interesting to use. Currently they look like you pushing buttons 2-5 to apply different conditions, such as stronger auto-attacks with longer cooldowns.
I hope developers see all user feedback and bring back the good old feeling to engineer (yeah like they are presented on wiki to new players), making it relevant and fun again not just for one elite spec, but for its essence.