"Weak strike" is not quite the right term I think. Even early strikes from new dies can show weakness on the reverses where the obverse portrait is highest. It's a phenomenon unique to the early series of George V and is often accompanied by a 'ghost' of the portrait appearing on the reverse, especially halfpennies, pennies, and shillings, and to a less extent sixpences. It's not a weak strike so much as an imbalance in the two sides of the design, which saw the portrait of George cut much too deep. For 'lion's nose' on shillings, read 'Britannia's face and chest' on the bronze. I would say that the ME coins are better struck, but whether that is purely down to the new portrait I don't know. I don't think the metal composition is the reason as that was .500 silver from 1920 onwards and there are plenty of weak 1920-1925 examples. Perhaps the new metal composition, being less dense, allowed the striking pressure to be increased. It's difficult to say as the reverses for ME coins are a single-year type, given that the entire coinage was redesigned for 1927, drastically so for silver. But I've seen many 1926ME shillings, they lack ghosting and seem to be pretty well struck up.