Yes, the good ol' Dk controversy again

I lean more towards pure spear dk. I myself and pure spear, but I have never tried hybrid so I can't tell you how well it works. From what I have seen, using a polearm would be fairly rare compared to the amount of time one would use a spear. In all of MS's bosses, spears have a huge advantage over polearms. Also, going pure spear, you would only need 1 weapon, instead of 2. I don't imagine someone would be using polearms much after himes, unless it proved more useful for mobbing at Peak. Where as spears you would use pretty much always. As for Final Attack, it is not very good at all for spearman/Dks. It seems like it would be helpful, but when it kicks in with slashblast it can really slow you down, especially when both slashblast and the final attack do a swing instead of a stab. However, if both a powerstrike and its resulting final attack are both stabs, you could kill a bit faster. My suggestion is to go pure spear seeing as you will be using spears more often than polearms, and you could get by with only a spear, and not a spear and polearm. Also the fact that crusher is significantly strong on bosses than fury.