There are two ways to install this hack: via Luma in-game patching or by rebuilding your rom. You can see this with Onmozu in chapter 3, and Gunter in the cutscene after chapter 3.
Several named enemies, and playable units in cutscenes, will not have their in-game models display properly.
this is because these classes never appeared as enemies in the base game and so have no generic portrait
Generic Great Masters and Butlers will have the hooded man portrait.
Enemy skills were generally not changed unless they were recruitable that map, needed Shadowgift to use their Nosferatu tomes, or had a -faire skill for a weapon type they could no longer use.
Further minor changes were made as needed for playability, such as adding in chest keys in Brithright 7 because the player no longer has any units with locktouch.
they will function correctly for relevant abilities, like Oboro's personal skill
No text was changed, so swapped classes will incorrectly be noted as their original faction.
Villager itself is unchanged, but has had its promotion options changed to wyvern lord and paladin, chosen because they were the only non-armored lance using classes available.
Nohr noble will be available in birthright, and hoshido noble in conquest.
the purpose of these three changes is to ensure all weapons available to the layer can actually be used. the exception is master ninja which has not been changed
Promoted and advanced classes can now reach A rank in their secondary weapon type, instead of B.