Complex sentence: He buys a black cloak from a peculiar shopkeeper, that he uses as his film character's cloak, however the cloak seems to instill in its wearer strange powers, something his co-star (Ingrid Pitt) quickly discovers.
Split into simpler sentences: He buys a black cloak to use as his film character's costume from a peculiar shopkeeper. The cloak seems to instill in its wearer strange powers, something his co-star (Ingrid Pitt) quickly discovers.