The H in honest is silent (as I said above it's pronounced 'onset'), so it is AN honest man. Same with hour and honor - AN hour and AN honor - because both are pronounced as if the H is not there. English is a notorious difficult language for pronunciation and spelling - what you see is not what you get, unlike Finnish. I am a English speaker and have taught English to non-English-speaking students and I am constantly amazed at how difficult it is (and in admiration of the many people who master it as a second or third language). In the case of honest, hour and honor, 'an' is used because it flows.