Should metal weapons conduct its electricity as well, like this creature?
Shock (Ex): A temperament generates so much electricity that its mere touch deals additional electricity damage. Temperaments' metallic weapons also conduct this electricity.
I was thinking about adding an armor bonus, based on the idea that the corpses that make up the Battlefield Mass are all wearing armour, and the mass itself is coated with more armour (including broken shields & weapons as well as actual armour).
Me, too. Start with +10 (or lower?), add +1 per 3 HD advanced?
That works for me as well. Something like this?
Integrated Armor (Ex): Most corpses a battlefield mass absorbs are armored, and as a result, bits and pieces of armor are integrated into its mass. When combined with the weapon fragments that dot its hide, this grants the battlefield undead mass a +10 armor bonus. This bonus increases by +1 for each 3 additional hit dice the mass gains.