Lydia is willing to leave. She is scared, and she knows it. So she'll help in ways other than fighting. I do think she's probably been trying to work with Yuffie on dodging/evasive maneuvers like she was with Kenshin before he went into stasis.

Definitely keeping that up after the whole battle and stuff too. Lydia'll take training from others, as there's a lot she wants to learn. I know Yuffie also wants her present before she goes, so Lydia'd make sure to get that to her before Lydia goes. :)