Sealing moisture in a hickory ramrod? Well, I learned, back in my stickbow making days, that hickory absorbs moisture, like any other wood, but doesn't release it, like other woods. That is the characteristic of hickory what makes hickory bows take a set so badly, if not sealed against moisture.
IMHO, leave hickory rods alone. Don't seal 'em, you are only sealing out moisture that gives hickory its flexibility.
As to soaking hic rods in kerosene and other concoctions, they may increase the flexibility of a rod while wet, but what happens to the wood when it dries out?
Does it retain the flexibility gained from soaking? To be honest, I dunno, never tried it.
So, the challenge is, soak a coupla rods for six months, let 'em dry for six months, then test 'em against unsealed rods left to absorb ambient moisture for the same time period.
To be honest, I dunno if there will be any difference in flexibility and resiliency.
The only way to find out is to test your theory of improving resiliency by soaking hic rods in several different concoctions, then testing against an unsealed control.
I, personally, don't have an attention span that will allow such an experiment over such a long time span. I can barely remember what I had for breakfast, much less remember when rods were put into a solution to soak...or why they were soaked, to begin with. So, someone with a longer attention span, than I, will have to perform this experiment.
God bless