What SG means about water being splashed on the tang causing a failure is that, as the steel is being heat-treated, the smith, or "kami", pours hot water onto the red-hot blade, aiming for the edge, especially on the curved part of the blade. This hardens the part where the water hits. Too much of this on the tang would make the tang hard and brittle, instead of softer and tough. This is theorized to be the reason for the few tang fractures that H.I. knives have had from time to time.
The key, I think, is to test the heck out of your specific blade soon after you get it. If it breaks, H.I. ordinarily replaces it. I make a point of doing some serious chopping with each H.I. khukuri i get, also chopping it into a log and leaning on it hard, this way and that, just to see if it'll break. I have NEVER had that happen. I figure that with hand-forged knives made out of springs from worn-out trucks, it's got to happen once in a while, and you'll occasionally see postings here about knives that's happened to. If it happens with yours, the answer is simple: send it back, and H.I. will probably replace it.
The only problem I've ever had with H.I. knives--and it's happened only two times, which is not much, given how many I've had--is excessive bending of the blades. One was a chainpuri, whose tip was softer than any steel I've ever seen, and the other was a tin chirra made by one of the new kamis very recently added to the H.I. shop. The chainpuri's blade was so thin that I'm not sure the problem with the tip was really a problem--it may just be that a blade that narrow and long can't really be hardened very well all the way to the tip without getting too brittle. Because what I use khukuris for tends to be hard chopping use on hard desert woods like olive and mesquite, I was less than confident in the blade, and ended up swapping it with H.I. for a tougher-use knife. So, I'm not sure I'd even call that "problem" a real problem with the knife. Might be that I just initially picked the wrong tool for the job.
The second time, I had a beautiful tin chirra, by Vim, I think, whose edge was developing waves right in the part that's usually hardest, after nothing but some ordinary wood-chopping. At first I tried to imagine it wasn't there, but it really was deforming under that use. With great regret (as it was otherwise such a beautiful knife), I sent it back, also, for replacement with another, tougher knife.
Bottom line: these are great knives, for (usually) great prices. H.I.'s guarantee is good enough that you actually CAN test them hard before you depend on them in the woods. In the very rare circumstance that there's a problem, they'll work with you to fix the problem. So, I have absolutely NO reservations in recommending H.I. khukuris to everybody who will listen.