Might be a little hard ....
The Vickers scale (I'll explain a little just now) is used to measure relative hardness - like most hardness tests. It is NOT, like most people think, always a good thing to have a very hard material. The way this works (in principle) is that the harder a material is, the smaller the crystals that forms the material. Which, in turn, makes it brittle. Having a 1550 on the vickers scale is a litlle to high imho - this is proven by the tensile strength - not a lot, once agin just my opinion.
The Vickers test uses a pretty nifty (although the technology is almost 40 years old) machine, that puts a ball - shaped load onto the material to be teted. You pre-stress the load, and then apply the final load, and by looking and comparing this microssopically you get a 'relative' hardness. In the days before Vickers, they used to file a metal / material, and if the material wore out, it was deemed 'soft'. On the other hand, if the file wore out, the material was deemed 'hard' ... how's THAT for simple??
The polymers would be strong enough - think of it this way: Kevlar is a polymer, interlaced by a honeycomb 'cloth', much the same way as fibreglass works. If that's not strong enough for you, hell, it's never gonna be strong enough. The main problem would more than likely be keeping the tip sharp - you won't be able to sharpen it yourself. The 'never-needs-sharpening' polymers is WAY too expensive to use for something as simple as a spearshaft. So, a slip - tip would more than likely be made out of Titanium or the like.
I'll go chat to a few techies, see what they think. It's been (urgh I feel old) 7 years since I studied mettalurgy / polymers. I'll need to refresh some memory here.
