Excalibur plus vampire charge broken

When you use the special vampire ability with the Excalibur. The Excalibur vanishes from your hand. Don’t know if its intentional but there should still be a warning. you can not vampire charge with the Excalibur or else the Excalibur will vanish. however with human flame charge, you still keep the Excalibur. the Excalibur only vanishes with vampire charge.