Honestly I don't know if I can get behind the idea he gave them defense jewelry (perhaps it is the case, I mean the jewelry does look...weird). Although he has been noted to giving normal items as well so the jewelry could of just been normal.
He also offered to give a set of rings for the their Dad and Uncle (Uncle is dead btw, I wonder if he died around the time MC mom and Deryl's mom did as well...) So it could of just been a normal gift but for twins only (maybe some sort of weird rule of his).
But yeah its said here that the Shopkeep gave someone a phone:
I sincerely doubt that phone had any magical or supernatural capabilities...although it'd be funny if it did. He just seems to accept anything as currency such as water in the case of Liz and Amber and for that random person flowers.