With all that power, you don't need to see. Just keep shooting wildly.
This thread seems not to have been properly addressed so far. People just list powers they don't like, but it seems the worst combo would be something that doesn't do much damage and doesn't synergize well with anything. So turrets and drones are logically off the table because they can easily be set up to do loads of damage. Likewise hex shield.
I'd be working on something like biotic sphere with Salarian decoy and tac scan. On a Warlord. With a Shuriken.
This fails your own criteria.
The weapon would have to be changed, but it would actually be pretty good. A warlord, in close combat, now gets a major damage boost from offensive bubble and tac scan, DR and potentially shield regen inside the bubble to make up for the lost tech armor, and a decoy to take the heat off