For 佩, what semantic notions underlie "to wear" and "to admire"?
According to 辞源 (see pictures below): wear something --&gt; keep something on one's body --&gt; remember something by heart --&gt; respect and admire something
It turns out that 佩 and 服 are actually very similar. Both mean both &quot;wear&quot; and &quot;admire&quot;.
Also, I just noticed that originally the object of 佩/佩服 is a thing, not a person. So you 佩/佩服 a person's courage, virtue, etc.
The example sentences in 《现代汉语词典》《现代汉语规范词典》 are still used in that way:
这种精神可敬可佩。
我真佩服他那种锲而不舍的精神。

But of course, nowadays you can also just 佩服 a person.
这姑娘真能干，我不禁暗暗地佩服她。