Unfortunately, that guide has a last modified date in June 2000, which would have been just after the UO:R era had started, but I remember it being the same way during t2a. I'd like to point out also that the cure potions here are based off of that chart at the bottom of the guide, so we are using it for other era accurate information.

My question to those who played in 98/99, do you remember being able to poison halberds, spears and other two-handed weapons?
Edit: I have looked through the patch notes and I have not found anything to suggest that what weapons could be poisoned had been changed, so the guide should be accurate.