I've seen some rather nice Buck 315 rigging knives lately at auction. I believe they were made by Camillus.
Good, solid, robust, sharp knives.
I had one exactly like it (probably a Camillus) when I was at sea back in the early seventies. Flawless performance.
For those who have not used a marlin spike (or marlinspike, if you prefer), it is not sharpened. The point is intentionally slightly blunted (some are actually rounded) so as not to damage rope fibers. It's used to separate strands of larger rope (or "line") for splicing and mid-knotting. So, a round, tapered shape is appropriate for that, but no sharp edges or points.
If you planned to use the punch/awl blade on a SAK or scout style knife, you'd want to file off the sharp point and edge, and even then it would probably a) not be large enough (these are big lines), and b) not be strong enough (the lateral force would possibly distort the scales/liners of the knife). I have an old scout knife where someone used one of the blades to pry, and the distortion is quite noticeable.
(Another fairly competent model is currently being produced by Rough Rider. The RR guys seem to have got the hang of quality and, although I wouldn't characterize theirs as "the best," it's probably a quite serviceable piece. I have no experience with this model from them, so I am only speculating. It's an import, and not from Italy. That puts some people off, and I understand that. Still, it's an option. If it turns out to be better than the price would indicate, then that's a pleasant surprise.)