Noobie Mod Questions (First Attempt to create a custom item)

I started messing around with Near Infinity for the first time today to try to create some custom items for my next BG:EE playthrough. As I was looking at the options for damage type for a sword, I noticed options for "Piercing or Slashing"...



I don't recall coming across any multi-damage type items in all my gameplay thus far... so I have some questions related to this.

1) Are there any existing weapons ingame with multi-damage types that I missed?
2) How would it work mechanically? If a weapon is piercing and slashing, does it use the best or worst case modifier against armour?
3) Is changing weapon damage type as simple as just changing this one variable?

Thanks in advance!