A little more to it

Remi had a weak constitution, which meant that she could not tolerate shocks or impacts very well. It was for that reason that she could not fight at all, and was restricted to long range weapons.

Apparently reaching the Initiate level would cure her of her condition, but until then she had to tolerate her physical weakness. But there was a reason why she was assigned to Nero's team. Her innate ability was simple yet extremely powerful: it was an enhanced control of aether.

She was so good, in fact, at controlling aether that if her body had not been so weak, she could have expedited her absorption of her innate card so much that she could have reached the Initiate realm in a matter of days.