My next project is the recently unlocked Turian Sentinel, that should work well for me.
Make sure you're specced into both Warp and Overload and you're good to go. I like to go 4 in tech armour and fitness, and max everything else.
For the warlord, he's much maligned but he's pretty good in gold and silver, and I've run into a couple of people who can make him shine on platinum (although I can't!). The key is knowing when enemies are primed for a sync kill:
Brutes: can happen after they've melee attacked or I think after they've roared, but both are inconsistant. The chances of them doing an instant kill are low compared to most other bosses and I don't usually have a problem as long as I take them down quickly one on one. If I charge into a group of them (which is likely as I turn into a nutjob when I'm using the Krolord) then it's far more likely one of them will get me.
Banshees: will normally sync kill immediately after a teleport and have a high chance of doing so. There's a brief window between jumps that a nimble character can exploit, but the warlord should keep away until they stop and start throwing warps- they're safe to attack then.
Atlases: will only ever sync kill after a melee attack. They stay primed until they raise their gun and start shooting again so don't close in with them until you see this.
Phantoms- they're primed after a melee attack and can stay primed for a little while, I've had them dodge or even get staggered, then immediately stab me with no warning. Best tactic is to use a charging melee to stagger them whilst they are using their palm blasters, then use the hammer before they recover, but if you miss get out of the way fast and don't take on two or more at once.
Scions: like atlases, are primed after a melee and remain so until they raise their cannon arm back up, so back off and wait until they start shooting again.
Praetorians: primed after a melee attack but it's so quick you often won't have time to get out of the way. If you try and get them when they're flying, biotic or electric hammer will cause them to put up their shield, and they'll usually just land and sync you. I find the best tactic is to nip in just as they start firing their lazers, give them a smack then back off before they have a chance to melee you. All other times just use your gun.
General tactics:
I would still take a good gun (any shotgun so you can have the omniblade mod) and shoot bosses as much as possible, only moving in to melee when you're sure it's safe. I also only go for the bosses when there's no other targets avaliable (with the exception of primes)
With your current manifest, the eviscerator or Scimitar would be ok for silver, but you'd be better off having the claymore, reegar, venom or graal to take him to gold.
An adrenaline module is far more valuable than cyclonics or any other armour mod for that matter. Without it, you might find it tough to get out of range of primed sync kill enemies fast enough.
No enemy can sync kill you if you're both on a ramp and at different levels. Be careful if the enemy (banshees especially) are at the top of a ramp on the flat surface as they can still get you if you're on the ramp and close enough to them.
Have fun with your reaper whack-a-mole