Lara held onto her sword, as well as the two emerald pearls. The situation was such that it could break into a battle anytime.
Perhaps she should give back the lesser glittering one of the emerald pearl to Hilton. Yes, she definitely should, however, he didn't seem the type who would stay still with only getting one, and providing him one where the situation could grow into battle was sheer foolishness.
Hilton had the emerald pearl for more time and knew how to use it better, while she only used it once. Though she succeeded in killing a monster much higher level than her, she doubted she could keep her sanity while using that stone. What if she attacked Enna holding that?
It would be any easier with him, either. No, her mind couldn't be trusted. She could feel the madness she drank in, barely keeping her sanity in check.