Pineapple on 03 February 2012
You're mostly just being lucky with Tana. You can compare their stats to the average stats for their levels (found here: http://serenesforest.net/fe8/average/tanafk.html and here: http://serenesforest.net/fe8/average/vanessafk.html ) for the two, and see.
At level 20 first tier, Tana has 4 more health, 2.5 more strength, but 2 less skill. As Vanessa comes a bit earlier, they're really pretty much exactly as good as each other.
