User blog comment:KuroAshi98/Fairy Tail Wikia Podcast 11/4/2014/@comment-4449950-20140414114026/@comment-24.52.205.15-20140415000404

Just curious, which source was used? Found the below from random Google search.

Guillao or Guille - "Prideful" or "Pride", respectively. (Puerto Rican Spanish). Marde - really don't think it will be the French meaning. It came up under Latin baby names as Warring. There is also the translation you found.

So perhaps it could be: Prideful sea/sea of pride, or warring pride? Perhaps a reference to his magic or attitude?