You can only activate the first effect, since while in your hand destiny hero - dark angel is no dragon. Since it becomes a dragon on the field, you can not activate it's effect due to the buster blader.
EDIT: Answering to your comment, if you mean DH Plasma, Then you are probably referring to its effect of negating opponents mosters effects. Since the Buster Blader negates only activated abilities, the continuous ability of Plasma is not negated. Then since Plasma negates Buster Blader, you could also activate it's second effect and equip him with the Buster Blader.