The spelling of the word "wast hand" is a combination of archaic language and regional variations. In modern English, the word would be spelled "waste hand," but historically, "wast" was used instead of "waste." The IPA phonetic transcription for "wast hand" would be /wɑːst hænd/, with the "a" in "wast" pronounced as a long "a" sound. The word "hand" is straightforward, with the "a" pronounced as a short "a" sound. This phrase, meaning "leftover helping" or "extra portion," may be unfamiliar to modern English speakers but has historical usage.
The term "wast hand" does not have an established etymology as it is not a commonly used or recognized term in English. It appears to be a combination of the word "wast" and "hand", but further context or clarification is needed to provide a more accurate response.