Items: "Defense: +1 (+0 eff.)", what makes it 0?

[Morikal]

So if the item gives Defense +1, why is it +0 effectively? (I assume that is what eff. means?)
Is there a way to raise the effective bonus up to the actual bonus of +1 in this case?

[Crim, The Red Thunder]

Defense moves in tiers, just like saves and power do. Specifically, each 20 points is a tier. One point raw = one point effective, for tier 1 (the first 20). For the next tier (next 20) two points raw = one point effective. For the tier after that (41-60), 3 points of raw = 1 point effective. This repeats as 4 points for 61-80, and 5 points for 81-100. I don't recall if it continues to escalate past that or stays at 5 a piece. It seldom comes up in standard gameplay.

This formula applies to defense, Mind, physical, and spellpower, as well as mental, magical, and physical saves.