I take it you haven't been bitten by one of them yet.

[Maybe he's been lucky or he bought some of that strong repellent they've been advertising lately, Terra figures, not knowing about Noctis' exceptional yelping and running skills.]

Their bite has some kind of effect on the heart.

[He presses his hand to the gold breastplate that reaches across his chest and forks down on each side.]

It seems like it's only temporary, but it's pretty unpleasant and possibly even dangerous while it lasts.

[In other words, totally bad enough for armor.]