Well, he was pretty trivial at 62: pulled with slow (resisted), sent in pet, FD to lose aggro, slowed again, Saryn's Kiss, Funeral Pyre, Shadowbond to keep the pet alive... went down in a minute or so, not long after FP wore off. Pet was at about 80% health at the end.
Although you may be correct in that this is the wrong picture of this phantom your other facts are wrong. When you say the "the same model as the other udeads" which exactly do you mean??? Do you mean the Skeleton undeads, the iksar undeads, or the Highborn Iksar looking undead??? In other words wtf you talking about willis??