In those sentences, I would assume fearful to mean that he is scared. If it meant he scares people, I would think the word fearsome should be used, or just scary.
I’m not sure about this, but I think that when we are talking about people or animals that are capable of feeling emotion, fearful usually means scared. When it is applied to nouns for abstract or inanimate things, then it usually means scary.
However, a Google search shows me some cases where fearful can mean scary even when applied to an animate noun. These appear to be limited in number, and are generally fixed, archaic-sounding phrases, such as “a fearful master”, “a fearful zealot”, etc. They seem to apply to people who are scary in general and to everybody, rather than in one specific instance.
Just a couple more points on the adjective fearful. To me fearful tends to be associated with the preposition of. A situation relating to what is now becoming sadly more common is when people are returning to the place where they lived after heavy bombing. Clearly you can imagine their feelings of anticipation and could express this as: They are fearful of what they are going to find. It is a sort of fear or fright in anticipation.
On the other hand similar to other adjectives like terriible, awful, frightful and so on, fearful has also been devalued and can be used quite casually in a phrase like: be in a fearful muddle - meaning you are in a very bad muddle.
Thanks Jamie. Thanks Alan.
I understand (hopefully).
…Quite often, when I come across with ambiguous cases, I have some strong feeling that natives do have some ‘secret agreement’ about them…
but acquisition of such kind of ‘native feeling’ is actually a difficult task…