Bonzuko

I think that the debate about Holmes’s baritsu/bartititsu fighting capabilities is interesting, but, ultimately, we must remember that he is a work of fiction.
Robin Hood and King Arthur have a rich folklore background, and there is even some debate about whether or not these men actually existed.
Not so with Holmes. He is entirely the creation of a British doctor and (essentially) pulp fiction writer. How Holmes managed to learn this obscure martial art is a question with a very simple answer: Doyle wrote that he knew it (spelled correctly or not). Why? Because it rounded out the profile of his eccentric and mysterious main character.
How did he know about it? Well, if he spelled it incorrectly, he probably didn’t know much about it. My guess was that – during the downtime of a cricket game – a well-traveled associate told an anecdote about a fighting style he had seen (or merely heard about it) abroad, and, of course, the description came through the filter of Western sensibilities.
It’s akin to debating how Superman shaves his super-stubble. It was probably nothing that Siegel or Schuster thought about, it was definitely not something they wrote about, and, though answered somewhat dissatisfactorily by later authors of the character, it has remarkably little to do with the endearing legend of the character.
Superman just doesn’t show up to fight Lex Luthor with five o’ clock shadow. We don’t really need to know how or why.

I don’t mean to diminish the power of the Holmes mythos. He is one of my favorite characters of all time. What I’m saying is that the ultimate answer to every mystery of Holmes’s biography is: “Because that’s what Sir Arthur decided to write.”