Every portrayal of Horth captures a different vibe. In this one, by Amy Midsomer and done for the cover of the Wattpad edition of Book 2: Righteous Anger, I see "young but dangerous". He's pretty serious. Wary, perhaps. But he's up for whatever's coming at him.
If you are new to Okal Rel, you may be wondering about the sword. Yes, it is science fiction -- I've gotten over flinching at space opera as a category, too -- but half of the universe adheres to Sword Law as a means of regulating conflict within their own cultural frameworks.
(If curious, Sword Law is explained a bit in a 2006 review of Righteous Anger by Neo-opsis Magazine.)