When someone blunders upon something, it means that they have made a mistake or stumbled upon something accidentally or unknowingly. The opposite of blundering upon something would be to intentionally seek it out or to carefully and thoughtfully approach it. Some antonyms for blunders upon could include: deliberately locating, precisely discovering, meticulously investigating, skillfully searching, carefully planning, thoughtfully exploring, systematically pursuing, intentionally uncovering, strategically revealing, or purposefully unveiling. It is important to approach tasks and situations with intention and focus rather than haphazardly stumbling into them. By doing so, individuals can achieve greater success and avoid unnecessary mistakes.