The phrase "wast remiss" may have an unusual spelling, but it's not as complicated as it looks. "Wast" is simply an archaic form of the word "were," replacing the "were" in "were remiss." "Remiss" is a word that means negligent or careless. When spoken, "wast" is pronounced as /wɑst/ while "remiss" is pronounced as /rɪˈmɪs/. So, the full phrase is pronounced as /wɑst rɪˈmɪs/. Despite its outdated spelling, "wast remiss" is just an old-fashioned way of saying "were careless."