I know that on most of my files Nina always is the one who can do the least. Her attack is very low, and she has no battle spells, so, here are some tips to raise Nina's attack. When you first get Nina in Winlan, just go off & battle some of the easy enemies, then go into the cave. Then you get the guards, so then every battle's experience is split into 3. But, find a fairly strong enemy, then make all 3 defend. And try and make the guards die. Heal Nina if she gets hit, don't heal the guards. So now, the 2 guards are dead, and Nina collects all exp points for every battle, I got Nina up to Level 11 that way. Then, later in the game, make sure to equip both Sashs that you find to raise her attack by 20. Now, Nina should have about 125-150 attack points, sure, it's not great, but hey! It's better than Bleu. Or, if you want, just use nina for healing. It's up to you.