I'll start with your lists, and modify it, giving reasons as I go.
Clothes - Nothing---Fine with that, clothes won't STOP anything that'd hit you.
Cloth Armor -
0 slash /
0 pierce---Cloth won't stop a thrust, but I will elaborate later. I'm assuming, for this, that you're thinking of tough cloth, rather than layered.
Leather Clothing -
1 slash /
0 pierce---Piercing attacks are MEANT to punch through armor, and clothing is NOT hardened leather, and certainly not studded.
Leather Armor-
2 slash /
1 pierce /
1 bludgeon---Now this is getting into true armors. The hardness factor may shield from some blunt damage, can catch a moderate slash, and may take an ill-aimed or weak thrust.
Chain - 3 slash /
1 pierce /
-1, or 0 bludgeon /
1 ballistic---No. Just no. Chain is meant to stop slashes, and broadhead arrow strikes. It COMPOUNDS BLUNT DAMAGE!!!! Unless you're wearing leather under it, then a blunt strike will drive chainmail rings INTO YOUR SKIN. Piercing shots of sufficient force (Force= force/area) can get through chain, by bursting the rings.
Splint - 3 slash /
2 pierce /
1 bludgeon / 1 ballistic---Gives base-armor equivalent protection for ballistic, piercing, and bludgeon, but gains points for slash and a bit for bludgeon from the metal strips.
Breastplate - 4 slash /
3 pierce / 2 bludgeon / 2 ballistic---You mean rigid plate armor. Serious armor, usually backed up with other types. Gives good protection, but a massively powerful thrust can punch through, same with a slashing strike from a higher "tier" of weapon material.
Minor Ring of Protection / Minor Invulnerable Potion / Painkillers - +1 to all--- I agree. People on super painkillers keep fighting until they are unable to move. (*Ahem* brainshot, muscle loss)
Lesser Ring of Protection / Lesser Invulnerable Potion - +2 to all--- Magic is a bit harder, I'll leave it up to you...but "Invulnerable" potions need a rename, because invulnerable is not ambiguous like protection.
Ring of Protection - +3 to all---Getting into higher tiers, sounds good.
Invulnerability Potion - +5 to all---Again, rename. Other than that, fine.
Greater Ring of Protection - +4 to all---OK with all protection rings and potions, although I'd say that it doesn't count towards magical damage.
Bracelet of the Elements -
4 to all elemental damage---Just in case there's more than 3 elements
Greater Invulnerability Potion - +10 to all---Yeah, okay. Crazy much?