There is an item buff called Pain Reliever sold by Dr. Pepper in Omega Sector. It boosts Weapon Defense by 300 for 30 minutes. However, in the game it's only +30 Weapon Defense. Was this intentional or is it a bug?
I don't know where you got 300 from but it should be 30. http://library.royals.ms/?page=items&search=pain reliever
I played the original Global MapleStory for a few years, before playing MapleRoyals. That's how I know it's 300. I used to buy a lot of it for my other other characters and it worked better than my Bless.
Yes, it's better than bless. Bless gives 20, this gives 30. If you were getting 300, you were playing a later version of maplestory, where the defense formula was changed. This item is working the way it's supposed to for maple royals.