The spelling of the word "wert extant" may seem unusual, but it follows the rules of Middle English orthography. In IPA phonetic transcription, it is written as /wɛrt ɛkstænt/. "Wert" is the archaic second person singular past tense of "be," and "extant" means still in existence. Together, the phrase means "you were still in existence." While this phrase may not be commonly used in modern English, it provides insight into the evolution of the language and its spelling conventions.
The phrase wert extant is actually a contraction of two words: wert and extant.
Wert is the archaic second-person singular past tense of the verb be in the English language. It was commonly used in Middle English and early Modern English, but has largely fallen out of use in contemporary English.
Extant, on the other hand, is a term that comes from Latin. It is derived from the verb exstare, which means to stand out or to be in existence. In English, extant is used to describe something that still exists, especially in written form.
So, when combined, wert extant essentially means you were in existence or you were still around.