Peter A Goldsbury
“BU Kaii (= a character formed from meaningful components). Combining 止 (a person’s footprint) with 戈 (hoko – a weapon), shows military advance holding a weapon. The original sense is ‘warfare’. A derivative meaning is ‘courage’.
In the distant past, there was the explanation that ‘stopping by the use of a weapon’ was the base meaning of BU ( = courage), but this was a mistake based on a different interpretation of the meaning of 止.” (『現代漢字語辞典』, p. 1279.
EDIT. There is a surplus 'by' in the above passage, which should read ‘stopping the use of a weapon.’ In other words, the revised base meaning of BU, and courage displayed, is stopping the one who is using the weapon.
However, as the second example shows, all you have are two (or three) radicals, with a hypothesis on the logic of the combination, but the logic behind the combination of the radicals is not identical to the meaning of the word in the language.