Trying to remember the name of a movie, but it escapes me... 1980's sci fi movie. Kid finds an alien weapon & a pendant necklace... Puts the weapon on his arm & the pendant around his neck. Runs amok, shooting the weapon, & in the process, becomes less & less human until he starts turning into an alien himself... Any ideas on the title of this movie?

Laserblast (1978) (http://www.imdb.com/title/tt0077834/)