User blog comment:GSFB/Terran Marines (Starcraft) vs Mobile Infantry (Starship Troopers)/@comment-6507091-20130215222022/@comment-5232784-20130215222758

Yes the combat knife won't do much against the Combat Suit, unless it could pierce the transparent vizor: and considering that Combat Knives in the Starship Troopers movievers can cut through Arachnid carapace (to a point), it's not impossible that they could do this with enough pressure applied.

Then again, we do not know what that Visor is made of (could be on par with "transparent aluminum of the Startrek Universe, or even stronger). I agree that the Knife, whether it can pierce visor or no, wil be of negligable use here in combat.