Manners/etiquette can actually be seen as low F. Strong Feeling doesn't need manners because it knows how to behave anyway. Manners exist so that you don't have to use Feeling. It depends of course what we mean by manners. There are different kinds.

If you are weak on Feeling and you are going to a funeral you better behave according to etiquette, you say the "correct" condolences, you bring flowers etc. Then you are fine and dont need to worry. A strong Feeler can improvise more, they know that they can handle the social situation without following strict etiquette.

I've sen ESEs going against the "proper" way of behaving because they had a "better" view and judgement of the situation.

I think social grace can be seen as Fe though.