Please clue me in... what belt types can have 4 sockets? (I'm interested in learning)!
Doh! Well that will teach me to regurgitate stuff from the itemlist without checking to see if it makes sense. Well the site does list the runeword under the all helms, body armors, and belts category and then in the description lists it as working in all armors/shields and then defines "all armors" as "This covers ALL forms of Armor both normal or class-specific : Helms & Circlets, Body Armor, Boots ,Belts and Gloves if made Socketed." I tried socketing some boots and gloves, but for some reason it just wouldn't work for me.
So make that Knight's Vigils body armor and shield for level 16 to 24 Meditation. Of if one accepts the runeword description blindly: helm, body armor, boots, belt, and gloves for level 40 to 60 Meditation.
I've been wrong enough... "the elemental skills"... does this include Cold Arow? Fireball? A PSapphire in my ring? Fists of Fire (it's melee, but is it 'elemental skill' also)?
Cold arrow would get a single boost from +% cold damage. Fireball would get a single boost from +% fire damage. A PSapphire in your ring or on your weapon would not benefit at all if you are using a ranged weapon attack (bow, crossbow, javelin, throwing) but would benefit from one application of +% cold damage when you attack in melee. I'm not real familiar with fists of fire, but I believe all three charge levels get at least one application of +% fire damage and the first charge may get a second application because the fire damage is carried on a weapon in melee.
Let me illustrate with enchant using hypothetical numbers.
Base enchant damage before fire mastery and +%fire damage: 100
Fire mastery + item granted +% fire damage
at time of casting enchant: +250%
Fire mastery + item granted +% fire damage
at time of striking: +175%
Enchant damage as calculated on skill tree page at time of casting enchant: 100 * (1.00 + 2.50) = 350
Enchant damage carried on ranged weapon hit: 350
Enchant damage carried on melee weapon hit: 350 * (1.00 + 1.75) = 962.5
If that isn't complicated enough for you, fire damage from whatever source (enchant, charms, equipment) is carried on both the arrow and explosion of exploding arrow. The same goes for cold damage and freezing arrow.
Minions do not benefit at all from your +% elemental damage or -% enemy resistance. This includes the assassin's traps that fire X times (all of the traps except fire blast and shock web) and the fire golem. It used to include the sorceress' hydra spell until Blizzard coded a fix for that specific skill. Corpse explosion also does not benefit from +% fire damage or -% enemy fire resistance, though conviction and lower resist still work for improving the fire damage actually dealt.