Fusion compiler vs Weeping Gemini S5

I just got grace weapon, and after searching around I found that it can be used on Burnice, that allows me to use Gemini on Jane since she’s missing a lot of Attack, however, do you think it is worth it to upgrade the weapon or just keep using Gemini.

And last question, in case of using fusion compiler, should I change her 5 disk from Fire dmg to Pen ratio? I saw that pen ratio is more valuable the more you have, and since the fusion compiler already gives 24% i was wondering if it would be better to change the 5 disk.

I have a tuning calibrator ready to get the pen ratio disk but also I wanted to ask if it would be worth it.