Possible Approaches
* Anagram: Is "WEQTETJU" an anagram for a word related to lighters or fire? Try rearranging the letters.
* Cipher: Could it be a simple code like a Caesar cipher (shifting letters by a certain number) or a more complex cipher?
* Hidden Message: Perhaps the letters themselves represent something else, like symbols or initials.
Let's try an anagram:
Rearranging the letters of "WEQTETJU" can give us "JET FUEL". This makes sense, as jet fuel is used to power lighters!
Therefore, the "secret" of the WEQTETJU lighter might be that it is fueled by jet fuel.
Disclaimer: This is a playful interpretation. There's no actual lighter with that name or fuel source.
If you have more context or clues, feel free to share them, and we can delve further into the mystery!