If she tried to take some of the piece that was amputated as they were leaving, she (or, you know, "someone," whoever) could get away with it. But she'd need to be sneaky to avoid the remaining Sha-Brytol noticing, as they'd react badly. She'd also need to be very careful, because this is still raw lyrium and therefore likely to result in blistering and nausea even with temporary exposure, and if she brought it too close to mages or rifters they would experience further adverse effects up to, like, death.