I looked at it like one would in actual medieval history. You are still a Baron, but you were also knighted since you basically asked to be sent as the tool of Baron Dorin to liberate the refugees (you are more bound to your current oath rather than made a servant). Barons could swear fealty to barons back in the day, under the right circumstances (usually when one needed a stronger baron's help desperately).
The way I see it is this... Syra knighted you and put you under oath since you gave her father the opportunity to do that, and he was still in awkward shock and she feared for how you might perceive his current frailty. She overstepped her bounds, since she is not a queen (who can knight someone), nor is she the ruler of the refugees (her father is). Technically, because she has no right to put you under oath, this was more ceremonial than real, although your actions in regards to the oath will either harm or help how honorable you seem to the people. On the other hand, there has been no sign of other nobles, and it may be that Syra is considering that she may become the highest ranking noble there... at least somewhere in the back of her mind. Of course whether these are just childish thoughts, or something that will develop further, is not certain yet.