How do you receive the Honourable Opponent and other insignias in LoL? I have had them at least once, but then they just disappeared and I have never gotten one again. I normally receive one or two Honourable Opponents every other game, and as far as Riot warnings go, I rarely get reported, and when I do it's some rager who reports everyone in my team.
You get honour whenever someone on either your team or the enemy team thinks you are worth giving a commendation to, which can be done in the post-game screen next to the "Report", "Gift", and "Add friend" buttons. Each player can give one commendation to another player, but has no limit on commendations in general.
You can give "Friendly", "Teamwork" or "Teaching" to a player on your team, or "Honorable Opponent" to a player on the enemy team.
It is primarily a counter to keep track of how many people thought you are an exceptional member of the community over the course of your LoL career. Other than that, earning plenty of commends can give you "crests"; An animation on your summoner profile.