Heureusement qu’en changeant la structure de la phrase il s’établit des différences, changez :

• le 1A en Il m’assoie,
• le 2A en Il m’étonne,
• supprimez à Tom dans 3B, (la phrase reste correcte)
  … les relations/distance entre A et B seront identiques dans les exemples choisis.

Pour chaque verbe, A représente une action d’un tiers sur moi, et B une action que j’exerce sur moi-même.

Dans les exemples :

• 1 – il y a action d’un tiers sur un autre (et non sur moi-même),
• 2 – un changement de il en vous qui met une distance de courtoisie, mais pas de personne,
• 3 – il y a une qualification de mon action qui n’existe pas dans les autres cas, donc une intensité dans la relation évoquée.

As far as I know, there is no hard classification between verbs based on the difference of meaning between their pronominal form and non-pronominal form. This in probably due in part to the fact that some verbs can only be reflexive, and that each verb can have multiple meaning. Furthermore, some verbs lost their pronominal meaning, but kept their pronominal form.

For example : s’en aller (leaving someplace) is a pronominal verb, but the pronoun has no meaning.

That said, we can classify pronominal verbs based on the meaning, in the context, of the pronoun.

• Reflexive Pronominal Verbs are the most common and appear when the subject act on itself. (Ex : Il se nourrit. “se nourrir” is here reflexive, since “he” feeds himself.)
• Reciprocal Pronominal Verbs appear when multiple subject act on each other. (Ex : Ils se battent. “se battre” is here reciprocal, since “they” fight each other.)
• Successive Pronominal Verbs appear when there is a notion of consecutivity. (Ex : Les jours se suivent. “se suivre” is successive, because the subject follow one-another.)
• Passive Pronominal Verbs appear when the subject is acted upon, but isn’t the actor. It often happens when the subject is inanimate. (Ex : le pain se vend bien. “se vendre” is passif in this context since bread obviously cannot sell itself.)

Please note that, based on the context, the same verb can be in different categories.

Concerning your examples :

• (2B) je m’étonne. Here, this sentence can have two meanings. It can either be “I surprise myself” (although we usually are more explicit by saying “Je m’étonne moi-même“) or “I am surprised”. In the first case, we have a Reflexive pronominal verb; in the other, we have a Passive pronominal verb.

• (3A & 3B) Agripper basically means grab, but can be used as a variant of accrocher where one of the objects must be the subject.

  • In (3A), the subject (he) grab the object (me).
  • In (3B), the subject (me) attach the primary object (me) to secondary objet (Tom). I could have juste said “J’agrippe Tom“, but by using a pronoun I created an emphasis on myself, indicated that I really latched on him.

Whenever you encounter a separation between the pronominal and non-pronominal form of the same verb, there is a big chance it is either due to a subtle difference in meaning between English and French, or a special case born from history (history loves to f**k up with language rules).