[@Dervish] To address your first point: 

[quote=@Thundercrash]

Afterwards, Tia was essentially adopted by a Turian named Matius Ruflin, a disgraced former captain who had deserted after a poor tactical decision resulted in his unit being annihilated by pirates.

[/quote]

Matius had deserted rather than admit responsibility for getting his men killed. It was this revelation on his deathbed that caused Tia to turn her back on him, since he hadn't lived up to the values he had instilled in her.

On your second point, I think I've already made some wording changes to clear that up. Tia was recruited by the Eclipse shortly after Matius's death, and was a member for the next 115 years of her life. I think it would be a little much to expect me to detail [u]everything[/u] that she did in that time span. 

For your third point, I must be wording things wrong. I don't mean to imply that Tia would kill people at the slightest offense done to her (it's kind of hard to get paid when you kill the guy who's supposed to give you your paycheck, and as you say, past a certain point you are considered a liability to the gang). What I'm going for is that, while her particular sense of honour did make her very reliable, it also made her something of a target for people who would use less scrupulous methods to get ahead, but would find that having a sense of honour does not mean she is naive.