The way I understand it Buddhism does not believe in such things as trinkets that bring luck, charms, spells, magic and the like. The use of these in Muay Thai( ie the Mongkong) is from Thai superstitions not Buddhist practice. A Tibeten Buddhist monk would tell you that such charms do not bring good fortune or luck. If it makes the person feel better they may "bless" something for them but this sort of practice is only for uneducated people and not part of true Buddhist practice. Buddhism seems to be influenced by and merges with or adapts to the traditional cultural practice of the country it is in and this is certinally the case for Thailand. It crux is about personal responsability to be a better person by being more compasionate and that has to be a good thing. There has never been a incident of international aggression/war carried out in the name of Buddhism nor do they try to convert people to their beliefs so get my approval. I have heard of "Christians for Muay Thai" trying to convert Thai's to Christianity which is just so wrong and arrogant on many levels.