I have had a couple ideas with engineers.... For PvP.
Give an engineer a taunt ability to grab aggro or force the target to change target to the user of the ability. The target of the engineer is forced to swap target to the engineer for a small amount of time, say 5 secs, after 5 secs the target gets an immunity for 30 secs from all other taunts. The power would have a 45 sec or so cooldown.
This ability could be made into a BOFF skill or a seperate capt power, or a built in ability of all cruisers.
Give an engineer the ability to tank for a group in pvp and pve... an ability to tranfer damage from a ally target to the engineer. Similar to Extend shields, but opperating in a different way. The engineer that uses this ability on an ally has 75% of there threat and 50% of there damage dealt to them transfered to the engineer that uses this ability. (This effect is already in-game with the mobius pet power, when the past copy is damaged that damage is transfered to you)
You could restrict the usage as such that the target of this power could not be affected by extend shields for balance. Build this power into EPS TRANSFER, or a seperate captn power.
Give an Engineer a passive ability that scales with damage taken, the more damage an engineer takes the more damage the engineer deals. Equivelant to sensor analysis. Couple this with the threat generation in the skill tree, that would enable the engineer to do dps, and tank in pve/pvp. But it would not allow for the engineer to take the burst dps role from a tactical captn, instead only build on the preasure dps that it is designed to do. But based on incoming damage.
Let me know what you think of my ideas, I have been discussing these at length with my fleet mates in the 106TH fleet.