To fela means in Old English idiom that no ground at all should have been conceded. And ofermod does not mean "overboldness", not even if we give full value to the ofer, remembering how strongly the taste and wisdom of the English (whatever their actions) rejected "excess". Whita scal geþyldig … ne næfre gielpes to georn, ær he geare cunne. Bur mod, though it may contain or imply courage, does not mean "boldness" any more than Middle English corage. It means "spirit", or when unqualified "high spirit", of which the most usual manifestation is pride. But in ofer-mod it is qualified, with disapproval: ofermod is in fact always a word of condemnation. In verse the noun occurs only twice, once applied to Beorhtnoth, and once to Lucifer.
fn6