Kyria was posing as Liam's servant, but was also tasked with keeping him safe, yeah. My sense of it is that this is less in the martial sense...though she'd constitute a last line of defense in that case too...and more of a 'make sure he doesn't do anything stupid, and notice incoming dangers that he doesn't' sense. But she's a bodyguard too. Just in a more pro-active sense. 
She was, as I recall, a member of a vassal House, essentially traded to Liam's family as a servant for some political sway and connections in court...

She was, as I recall, a member of a vassal House, essentially traded to Liam's family as a servant for some political sway and connections in court...