The Athenian general Nicias in the history of Thucydides was not the superstitious man scared by a lunar eclipse in the biography of Plutarch

Thucydidean Nicias is presented as a rational general and tactician ... he has no relation to Plutarch’s fearful and superstitious character. ... Nicias’ decision to side with the seers may have been a rationally based choice with the aim of avoiding mutiny in his army – a mutiny which would have proven fatal to their survival. ... the historian shows profound admiration of Nicias in a funerary epigram in which he praises the latter as a man of exceptional arete. ... Nicias’ partiality to the manteis was considered a weakness by the historian, but it was a tiny part of his overall positive presentation: we might call it a mere parenthesis, rather than a judgment long held back, as the authoritative commentator [Hornblower] puts it.

-- Nanno Marinatos, A NOTE ON THE THEIASMOS OF NICIAS IN THUCYDIDES, C&M 70 (2022) 1-16.