The spelling of "haddest advantage" may seem confusing at first glance. However, its pronunciation can be broken down using IPA phonetic transcription. "Haddest" is pronounced as /ˈhadəst/, with the stress on the first syllable. This archaic form is the second person singular past tense of "have". "Advantage", on the other hand, is pronounced as /ədˈvantɪdʒ/, with the stress on the second syllable. It means a beneficial factor or circumstance. The phrase "haddest advantage" implies having an upper hand or superiority over others.
The phrase haddest advantage is an example of Early Modern English (16th and 17th century) verb conjugation. It is formed by combining the second person singular past tense of the verb to have and the noun advantage.
The word had, in this case, comes from the Old English word hæfde, which is the past tense of habban. Hæfde evolved into Middle English hadde and then further into Modern English had.
The word advantage has its roots in Old French. It stems from the Latin word advantageium, which means to turn toward or to profit. From Latin, it entered Old French as avantage, and then Middle English as avauntage. Eventually, in Modern English, it settled into its current spelling and pronunciation as advantage.