To clarify what the guys above are saying, HI knives are usually one of two tang styles. The traditional style is called rat-tail tang, where the tang thins down at the beginning of the handle, and tapers as it reaches the bottom. The end of the tang pokes through the handle material, and then a butt cap is secured with laha and some good peening of the tang. Think like a Ka-Bar design. The other handle style is the Chiruwa style. This style is what we westerners are used to calling "full-tang," in that the tang extends both the full length and WIDTH of the handle. Do not be confused though, both the Chiruwa and traditional rat-tail tang extend the full length of the handle, and are therefore full tang as opposed to partial tang, which definitely are not recommended.
There is a key difference performance-wise though. A Chiruwa model of the same length as a traditional will be heavier, and/or have its center of mass closer to the handle. To me, that is directly negating much of the design and original intention of the blade. The full wood handles also absorb shock, which is yet another benefit.
When in doubt, think of it this way: the rat-tail tang has been used on this kind of knife for a few hundred years now. If it was not an effective design, it would most certainly have been changed by now. The fact that HI makes knives with the Chiruwa handle is, in my opinion, only because it appeals to us westerners.
Now to answer your question in short, pins/rivets means Chiruwa style, no pins means traditional rat-tail. And the knives with the carved ends that I've seen have Chiruwa handles, the tang just doesn't extend the last little bit. Those are more like a "full-tang" knife with an extended handle as opposed to a partial-tang.
As Bookie said, buy any model with confidence. Even the blems are tougher than most any production knife on the market.