On May 1 the Most Rev. Malcolm McMahon, OP, formerly bishop of Nottingham, was installed as the 12th archbishop of Liverpool, England. His coat of arms is depicted on the cathedra of the metropolitan cathedral. It is interesting how the personal arms impale the arms of the See but both are then placed under one chief.
Actually they aren’t his personal arms at all at sinister: that’s the (old form of the) Dominican Order’s arms! So I think that the chief is the only personal element (at least the only one I don’t recognise). That’s unusual; I’ve seen quite a few examples a “chief of religion” before but this is the first time I’ve seen (what may be) the opposite!
I disagree with you. While you are quite correct that the arms of the Order of Preachers is being used that doesn’t mean it isn’t really part of his personal arms. What the Archbishop has done is to incorporate the older arms of the OP into his personal arms. That’s not a correct thing to do but he’s following a precedent set by many, many bishops.