That icon is designated for "Trial Adventurers."
That could either mean someone trying out the game in an officially-sponsored program, or characters granted to the press for easy coverage on the game.
For example, IGN recently covered new additions to Chains of Promathia, and in their screenshots, their characters had the "Trial Adventurer" icon abover their head.
If you're confused about what some icons may mean, check out the details on the Mentor system
here.