http://www.vgrevolution.com/2013/07/dark-souls-ii-hands-on-preview/
http://www.examiner.com/article/dark-souls-2-weapon-customization-and-upgrade-details-posted
Of note, VGRev says
Whereas Examiner (who's referencing the VGRev article) writes
Now I want to focus on this briefly: "Both properties should provide lingering damages to enemies who are vulnerable".
They way this is worded makes it sound like not only will poison be an upgrade path (rather than a resin, or maybe both) and that it will still be damage over time, but that Fire will be damage over time too.
I can't find any source for where they got this from other than the VGRev article, and it's most likely just be misleading writing, so I'm not putting much stock in it.
More importantly though, it seems that you can combine two elements. Whether there will be major and minor elements (eg Fire/Lightning as a major and Poison/Bleed as a Minor) to combine or whether it's just any two elements I'm not sure, but it will be interesting to see how it plays out.
http://www.examiner.com/article/dark-souls-2-weapon-customization-and-upgrade-details-posted
Of note, VGRev says
Deeper weapon customization. You’re now able to combine poison and fire together on your sword as well as many different types of combinations.
Whereas Examiner (who's referencing the VGRev article) writes
In “Dark Souls 2,” players can now add two different elements together when they upgrade their weapons. One example that was used is being able to combine the effects of fire and poison. Both properties should provide lingering damages to enemies who are vulnerable.
Now I want to focus on this briefly: "Both properties should provide lingering damages to enemies who are vulnerable".
They way this is worded makes it sound like not only will poison be an upgrade path (rather than a resin, or maybe both) and that it will still be damage over time, but that Fire will be damage over time too.
I can't find any source for where they got this from other than the VGRev article, and it's most likely just be misleading writing, so I'm not putting much stock in it.
More importantly though, it seems that you can combine two elements. Whether there will be major and minor elements (eg Fire/Lightning as a major and Poison/Bleed as a Minor) to combine or whether it's just any two elements I'm not sure, but it will be interesting to see how it plays out.