Icarus's body is data but there was a way to bring what was in the data world, that's why Gustang sent Baam there in the first place. Gustang has some privileges so he might be able to do something. I know artificial hax won't be good forever, but against most of the Regulars it would help her for a good while.She is definitely wasting a wish on being pretty, icarus body got erased its just data anyway, Gustang is a scientist he can do something similar or close, who knows he might have some zahard blood somewhere, an Emile ignition weapon working from within isn't enough, Rachel doesn't like to train nor does she have enough real combat experience, artificial hax can only go so far in real fights, the stingray was never hers zahard recognized it instantly, so Gustang always knew the outcome regardless of what happened who died or live, he was gonna get the bracelet and zahard was gonna give orders in retaliation.
The thorns aren't that hard to control imo, Bam is just too weak so the thorns are constantly trying to regulate there power for him, anytime he is trouble or losing it, they operate above his limits to support his wishes been that way since he got them, also imo no one but bam can get them to work, I know it been said that any irregular can use it, but it would be silly that none of the FH haven't over the years casually tried to wake one of the fragments, also the God outside would be incompetent if he can't put a simple security lock on it until bam arrives.
It's weird to say that Baam is too weak, his physical abilities are average compared to 10F members but his physical training is good(and you probably need more than stamina to wield the Thorn anyway). If it was hard for Baam to wield a single fragment like that then it would be even harder for Rachel. Of course the FHs would be able to wield the Thorn easily, but they are Rankers unlike Baam and Rachel, even now Baam has a hard time with two fragments. Rachel will need to get stronger if she really plans to wield the Thorn.