When my mam died, we had 8 grandchildren from aged 5 to 12 between me & my sisters to dress for the funeral. It didn't seem appropriate to dress them in black or equally all turn up in different colours as if it wasn't a "thought about" occasion, they were all dressed in their school uniforms (3 different school colours) but loads of people commented on how this was a wonderful mark of respect that was age appropriate and not sombre. School uniform definately for me. You will probably find that he himself will make sure his hair is done, uniform straighter than normal and posture better, because as you say he knows the etiquette, no one knows what to say in these situations, so even though he may think it's just him who doesn't know what to say, feel or do, probably the rest of the room are bewildered too. Best Wishes