COMPARING OLD VS NEW. The off-hand is the new version and I used the MH old version. (I don't have the OH old version but showed the new version completely in the second image.)
Results are... Well... The shield facing inwards literally goes into the character's head and clips into their shoulders. The old version in fact adds height as it's one of the largest blades. Not 100% as I do not have all the appearances unlocked to test out but comparing it to Havoc's hidden skin is amusing.
edit: Old WoA do use a sword model. Shown in the stance for combat. If someone has both pairs of the old WoA you can test this out yourself.
Comparing size: