well lets look over the facts of the situation, remember marines don't think like normal people in the least, they hold their honor and the honor of their chapter above all else, only their Primarch and Emperor mean more to the., pain, suffering and death mean absolutely nothing to a marine, the whole "Death before Dishonor" is a motto most if not all Marines live by, though each chapter's sense of honor differs.<br/><br/>now lets cover a few reasons as to why he would arrive to the dinner area fully armed.<br/><br/>1) first and fore most, he is not there to eat, he is just there to listen to mission briefing and to protect Avorn.<br/><br/>2) in a room, that has three extremely deadly close combat expert xenos, a Traitor(though by birth alone) and a Pysker. is it truly that surprising the a Space Marine brings weapons, not as a show of force, but as an insurce that if things go wrong, he can at least buy Avorn some time to get out of the room?<br/><br/>3) Darvius just doesn't care what anyone would think about his look, and I am guess he would have done this a few times already,not always eating with the others.<br/><br/>4) Marine don't really know the meaning of tactful in the same sense as a normal person would. having been raised from a young age, right before/during puberty, his 200+ years have mostly been with the chapter. meaning he would have given up all ties to humanity other than protecting it. making him in the very least socially awkward. though Darvius would have a slightly better grasp now after having spent years among "normals"(terms fits here loosely).<br/><br/>so in Darvius's eyes he is in the right bringing weapons, he does not answer to the chain of command as a Guardsmen would have. in truth the Chapter answer only to themselves and the Lord of Terra(Inquisition). even then they are more likely to tell them to fuck off, for only a Chapter Master can order the chapter around. they are very much an independent faction within the Imperium, going where they want, and doing what they want.<br/>