I cannot speak for the Pierce Brosnan but I do have some reservations about the Des. It's a small space to write an autograph but even so I don't like it in comparison with others I have had.
Sorry, I dont think either signatures are authentic. I have gotten both personally in the past & although Brosnan is sometimes very hard to authenticate, he doesnt normally write in a straight line from left to right slowly. The Llewelyn has been slowly drawn also. But this is just my opinion.