The battle circle is tough, even for a Guardian with a high strength.
I've played as a Consular in all but 1 game (my current one) so I know alot about fighting as a real underdog in the battle circle.
What I'd suggest is:
1)If the person you're fighting allows melee weapons, choose a very effective weapon like the Shyarn or Trandoshan Double blades, etc. that deal alot of damage.
2)Use armor that has bonuses on piercing, bludgeoning, etc.
3)Stock up on items that deal with things purely made for combat: Fortitude, Will Saves, etc. as well as Strength, Defense, and Dexterity. Constitution also helps alot.
Other than that pure luck is what you need. It took me a while to master the battle circle but even as a low- strength consular you can make it through. If none of this works though, do what everybody is suggesting, turn on a Mandalorian Melee shield before you speak to the sergeant or take ridiculous amounts of Stims.