After a quick examination of the necklace, he let it vanish into his literal storage dimension dimension. "Thank you, that is very kind to give such a remarkable device away." He would examine it more carefully when eyes were not turned on him. For his studies, Loki preferred privacy.
"Ah, as for your this...," Loki said and held up the small black device with a button. "It gives me an electric shock. My heart beat needs to be started... manually so to say..." It had taken him hours of practise to control his own heart muscles. "But I do not want to walk around, actively thinking about keeping my heart going. A shock resets it and it starts to run on automatic impulses." The god was no medic. He did not know why it worked and he hardly cared about it. If meant he was alive and that was all that mattered. Being alive made death so much sweeter.