She is a murderous bastard who was also helping a bunch of like-minded murderous bastard and there is absolutely nothing to suggest that she's turned over a new leaf or even had a change of heart on the whole thing.
By my reading of her so far she is -at best- ruthlessly pragmatic, which is to say she'll betray us the moment it's more convenient for her to do so.
What I think is more likely is that she's a disaffected coward who'll steal our shit and then go on the run.
As has been said before, we have no confirmation of any of that. We don't even know if she has killed someone indirectly, much less directly, and she doesn't seem to really follow the nazi doctrine, so all we know about her is this: she made part of the alchemists, she was captured by our girls instead of killed, she tried to lie and failed, then helped us do a curse breaking and almost died for it, now she has three pieces of cursed (or ex cursed) sword in her body. It's not much, and really doesn't say much about her personality. For all we know alchemists could be mind controlled, pargmatic or each following a diferent dream (like reviving a dead mom, alchemy) because we know almost nothing of their group or even the groups ideologies.
Thus, yes, we should keep an eye on her and not simply trust her, but killing her for something we don't even know she did... Doesn't sit right with me. And that's another thing about power, you know? It's harder to keep someone contained than to kill them, but we do have enough power in our base to contain her, and this should only grow, with more girls and better equipment, maybe even base protections.
I mean, while this is true, the counterpart truth I feel people taking your position are ignoring is that wands still don't beat out trinkets.
Both are critical to have, both are equally 'really do not want to do without', and we just made two wands. We should be making other stuff next because that other stuff is needed just as badly as more wands.
I'll disagree here. Trinkets and bombs are not 'really do not want to do without', the only reason you even see it as this is because we started with it on lv3. Think about it, if we had all our craftings on lvl1, and seeing their effects (AKA: wand main weapon, costume armor with extras, trinket bits of diferent extras, bombs big effects but consumable) a trinket is explicitly not the 'necessary' kind, it is the extra that can make them stronger, it is the acessory in a rpg game, it can make a lot of difference, but is not owrth much without the rest.
That said, it would be if they were all the same level, they aren't, right now trinkets are probably still better for protecting our girls than lvl1 costumes, so I'll still be voting for a trinket next turn, especially since we have a girl that seems to always get hurt, who wants to play with illusions... Also because we got the wand situation under control.