My understanding (which is very rudimentary) is that swords could be ordered in a variety of styles, finishes, etc. I suppose that this one was ordered with some "non-standard" features such as shark skin grip & scabbard, naval style pommel, etc. to make it different or unique. Without knowing who ordered it, when and why, etc I don't think we'll ever know why it's the way it is. There are many styles of swords that are "one offs" or whatever that were special ordered for individuals.
I'm intrigued by the comment about the oak leaves vs. laurels being an indicator of the sword being made (or at least assembled by) Horstmann. I need to read more about that.