[quote=TentacleLord]
2.Imbue's a rather high skill for a solider of all things, being tier one. That being said, exactly how much would this increased magical capacity be? For someone that doesn't use tomes, I can't imagine it'd be very useful in the overall scheme of things. 
[/quote]

Remember Fiona from Radiant Dawn? Like that. She's a tier 1 Cavalier with like 6 magic, who has Imbue. So, it's nice, but it doesn't make much difference.... Until you throw a bunch of spirit dusts and bonus experience at her to make her an immortal goddess. Of course, us not having spirit dust or bonus experience, the main point is that Imbue would be OP on a spellcaster, but is interesting flavor on a martial character.

As for age, she's a dragon-blooded laguz, so the answer is "Not since the dawn of time, but anything within the last few centuries is fair game."