The Red Iron Blade is a very good lvl 30 2Hand-Sword. You don't need Items to upgrade the RIB, you just need money. The RIB can have Damage or Skill Damage. The max. Damage is 60%. The max. Skill Damage is 35%. Many people use the RIB to break Metin-Stones. A RIB+9 with 35 Damage and Stones+4 make more Damage than a Partisan+9. The RIB is often use in Poly Marbles. You can get the RIB from monsters in Nula Valley like Esoteric Arahan or Esoteric Arahan Fighter and Chief Esoteric Arahan.
e.g.: You have a RIB with 30% Damage without Stones. You look into your AP. There is standing 1.000-1.100. Now the Question: How much Damage i will make with the RIB 30% Damage? It's very easy. The Standart-Damage is 1000-1100. So that is 100%. Now you add 30%. Thats 130%. 130% from 1000-1100 is 1300-1430.