Not a PushoverNaminé may not have impressive physical strength, but I think it's hardly fair to say she is always a weak character. Not paralyzed by her fear of loneliness, she stands up for what she believes in on numerous occasions. She is no longer the caged bird from before. What Naminé lacks in physical strength, she ultimately makes up in the strength of her heart that grows once she overcomes her debilitating fear.
The first sign of strength that Naminé shows is her decision to confront Sora and tell him everything. I believe that this took a lot of willpower for two reasons. First, though she felt guilty, knowing Sora was looking for her and considered her to be very important was like a dream to her. She had been alone for so long, so just the idea of someone caring so much that they would fight through countless obstacles to reach her would make her beyond happy. She not only would lose Sora's feelings, but she also ran the high chance that he would be mad or hate her. Secondly, telling Sora the truth would deliberately disobey Marluxia's orders and therefore she would be punished and lose her chance of freedom. Despite the consequences, Naminé ultimately confronts Sora because she knows it is the right thing to do and that she needs to begin the process of making things right. If she were the same weak-willed person as when she was born, I do not believe she would have made the same decision.
Naturally, once Larxene finds out what Naminé has done she is infuriated. Larxene guilt trips her in front of Sora and she falls silent. She knows she cannot refute her words since they are true. However, once Larxene threatens to eliminate him, Naminé rushes in front of him with her arms out in order to protect him. Clearly she knows that she is no match for Larxene, but it does not matter to her. She cares for Sora and does not want to see him get hurt anymore than he already has. What she had been helping Organization XIII do was not right and she was not going to sit back idly and let it happen any longer.
In Sora's absence, Marluxia captures Naminé once more. When he finally reaches her, Marluxia orders her to erase his memories. Naminé refuses because she knows doing so would destroy his heart. Angrily but firmly she tells Marluxia that she does not care what happens to her anymore. She absolutely will not hurt Sora anymore. Once fearful and obedient to the man in front of her, Naminé voices her will and deliberately goes against what he is saying. Her desire to protect Sora overcomes her fear of being alone as well as any fear about what may happen to her. Obviously she is not the same person as she was before. Not that I think Naminé is a bad person by nature (quite the opposite, really), but I honestly feel she may have followed through if he had ordered her to do so before she met Sora in person. Facing Marluxia directly and standing up to him really showed how much she had grown since she was brought into existence. She had no intention of being a pushover any longer.
Though working behind the scenes mostly, Naminé's strength of heart shines through in subsequent games as well. She struggles against DiZ' and Riku's wishes in order to tell Roxas the truth about his existence as a nobody and she meets with Xion even though DiZ was against it. Naminé is no longer someone who simply follows orders. She acts on her own accord and does what she thinks is right no matter what the cost may be to herself. Though it may be more reckless than not, I honestly think that her willpower is so strong that she would stand up to anything if necessary to do something she felt had to be done. When she is helping Kairi escape from her prison, Naminé is quick to take a fighting stance alongside her when confronted by Saïx. She does not run away in hopes of someone saving her, nor does she give in to his demands. Similarly to the situation with Larxene and Marluxia, she must know in the back of her head that she has no chance in actually defeating him. Even so, she knows she has to get Kairi to safety and is willing to sacrifice herself in order to meet her goal.
Both Kairi and Naminé get a bad rap for being weak and relying on others to protect them. All things considered, however, I do not feel it is fair to judge them in such a way. Yeah, maybe they are not physically strong and would not do well fighting. But that does not mean they are simply pushovers, either. They both are very strong willed, have powerful hearts and find strength in caring for others. They most certainly are not cowards by any means. Kairi is implied to be the next keyblade wielder at the end of Dream Drop Distance, so in all honesty, I would not be surprised if Naminé would have had the same ability (like Roxas did from Sora) if she were still separate from Kairi. I find it ironic how many people seem to be quick to judge the characters based on their physical abilities when Kingdom Hearts is a series that stresses the importance of the strength of heart. All in all, Naminé may have started off as a weak character, but it would be hard to argue that she does not grow into a strong one. The Naminé who obeyed orders out of fear is almost a completely different character from the Naminé who fights for what she believes in.