As far as I can recall, he's not described as throwing it, nor does it generally sound throwable, so I probably wouldn't classify it as a spear.
Yeah, I'm thinking Glaive, but able to choose between piercing or slashing. Probably masterwork quality (does that exist in this edition?).
Just make sure you add a decent helmet - it may come in handy!
The problem is the D&D spear poorly emulates the weapon used. The trident is even worse being just a crap weapon all around, a glaring oversight in game design.
Glaive is probably the closest approximation, since that gives you the tricks you'd want with the polearm feat. add the finess property and you're good to go.