The stare wasn't really a display of power or danger, but more one if curiosity. And how he grabbed his Bolter was just a mere act of safety, same goes for his left arm turning into a Chainsword. Imagine if they were attacked while he was practically unarmed. Although I guess Space Marines are never truly unarmed; they'll still have their fists. "Kolandra, eh? Interesting name... I like it. Rolls off the tongue very nicely... Kolandrrrrraaa..." He experimentally extends the 'R', much like a purr. It was in no way meant to offend; he even seemed to be rather innocent.