User blog:Apoelpaoole/X-Bracelet on Mihawk-Doflamingo-Blueno

Link to the picture=> http://sphotos-d.ak.fbcdn.net/hphotos-ak-snc6/196401_319446201500571_1036366026_n.jpg .Here are the chapters as well=> http://www.mangaday.com/One-Piece/504/07/ http://www.mangaday.com/One-Piece/592/03/ (couldn't find Blueno's)

So a reviewer named CodeProvider(don't give me any credit for my observations skills) noticed that on Mihawk's-Doflamingo's-Blueno's hand there is an X shaped bracelet-tattoo. I believe it represents something because Oda wouldn't just draw something so detailed in the same place of 3 different characters without a proper reason.

What it could represent? A former crew that is not active anymore or a secret organisation. Something they sweared to do beetween them and the mark is a sign to remind them?
 * probably other people wear/have it as well?

What are ur opinions about it?(I can understand if some people find it stupid and believe that Oda just likes to draw that)