Perhaps it is different in the lands you hail from? Where I grew up, we didn't find threats and boasts very funny. I do know that humor can vary from place to place, though, so maybe this is just a terrible misunderstanding and you didn't realize that nobody but you would laugh. I know I would feel so sad and embarassed if I did that, and I'm sorry if I make you feel more bad.
But... telling people to beware your deep water sounds very much like a threat, and if it isn't one, it's yet another arrogant remark. I know I'm being kinda rude, but you haven't made the most glittering first impression. Maybe things would be better if you would stop accusing people of being egotistical while injecting allusions to your battle prowess into just about everything you say...there are many seasoned warriors here, and it's no surprise some have taken your words as an insult. Also, nobody likes to think their friend might be in trouble because of the new guy in town.
I'm not saying you've made people angry on purpose or that your head is really that swollen with your own greatness. I'm just letting you know that's the impression you give so that maybe you can work on it and make it easier for people to get to know and like the real you!