Charles is not the Duke of Edinburgh. There is no Duke of Edinburgh. When Charles became King the Dukedom merged in the Crown and became vacant (or available so to speak).
That is why Charles could make Edward the Duke of Edinburgh.
For the news itself, it is not suprising. It is well known that Charles does not really like Andrew and Edward. There is a lot of resentment on his part.
He only likes his younger sister, Anne, and is quite intimidated by her. He grew up with Anne. He never grew up with Andrew and Edward like he did with Anne.
Charles loved his Granny, the Queen Mum more than he liked Philip, Andrew, Edward and even his own sons.
