I played both KotORs far more than was healthy back in the day.
Just something about them sucked me in; I don't think I'd responded to a game so viscerally since Fallout 2. I like using all the characters as much as I can, both as a challenge (oh boy is there almost no good way to use T3-M4) and because of the interactions you can see with different people in different situations. Next time through, try taking Canderous and HK-47 through your trials at the Sith Academy. They have some priceless stuff to say. (Although Canderous threatening to wring Jolee's neck is pretty hard to top, I have to admit.)
Yeah, Bacca's Blade is VERY powerful, but it's not the champion of melee weapons. Check out Yavin after the first restock (I think it happens after you've found two Star Maps, not including Dantooine, and it definitely happens a second time after you've found all the Star Maps and are about to leave for the Star Forge) -- you'll find the unbelievable Baragwin Assault Blade, which is so good I've considered letting my PC use one instead of a second lightsaber. Canderous built as a melee fighter with two Baragwin Assault Blades (or just one and Bacca's Blade), Heavy Combat Exoskeleton, and a Nerve Amplifier Belt is almost unstoppable. Carth is almost as good as a melee fighter, but Canderous is better, and if you're planning on using both of them it can spread out the better swords a little too thin. Carth with Cassus Fett's Blaster, the Sith Assassin Pistol dropped by Admiral Karath, and dressed in the Environmental Bastion Suit is pretty badass.
All that being said, I've never been able to use Mission effectively. I feel like there must be some way, because there's a huge amount of high octane gear that is obviously geared toward Scoundrels -- most of the Genoharadan stuff, the Baragwin Shadow Armor (which can be bought immediately upon reaching Yavin and which is not too pricey), the more powerful stealth units -- and yet she simply doesn't have the hit points to withstand serious damage. Even with a high Defense -- even without spending lots of time on her she's liable to have the highest defense of all your party at the end of the game -- she still gets whomped on. She doesn't get enough feats to make focusing on Toughness worthwhile, and even WITH them she still gets her ass kicked. She'd likely be better as a melee fighter, but her Strength is subpar and she already has pre-selected feats to guide her toward ranged combat. Canderous and Carth are easy to rebuild as melee fighters because they get so many feats, but poor Mission doesn't have that luxury.
It might just be a combination of ranged weapons being awful in the first game and the Stealth system being poorly implemented. Ideally what you'd do with Mission is have her move in under a stealth field, sneak attack with Critical Shot/Strike, then kill the mook while he's stunned. But using Stealth takes an ungodly amount of time AND once she's de-cloaked she's in hostile territory, far from stronger characters who can have her back, and way too frail to deal with the situation.
It's a shame. She's a pretty well-written character. If anyone ever built her well, I'd love to hear about it.