I understand where you are coming from
Let me explain a little about the bias
Sin has 5 attacking skill ; Sura has 2 ( I know dispel but that is different)
The thing is this weaponary Sura att boss but boss has high sword defend while sin att boss on poly when boss has lowest bow defend with sin having extra 35 present extra att. The damage attacked has lots of difference which I am sure you are aware of.
Most players likes to kill boss or att boss area which is more valuable than metin. The thing is being a player of Sura it is very hard and let face it with proper gear any char can kill any boss so there is really no difference in Sura so call great defence against other class unless in some complicated map.
As far as PvP I am aware of dispel but depends on what kind of weapon. You may argue Sura uses blade but let face it most player like to run away which makes it harder to really hit properly and blade damage is low too with come level of resistance.
As for sword . It is still sword meaning the enemies just need sword defend
Unlike other class like u need multi defence type. Sura use either rune or dragon tooth but honestly not really much difference unlike overrated sin .
I am here to suggest that weaponary Sura is really being degraded by metin2 that all and hope your guys look into it and improve it to be somewhat better.
My suggestion is to improve Sura pvm damage and PvP.
I understand you like sin ; but I hope u can make it such there difference between sin damage and Sura damage difference not far off.
Thank you for your time and effort in replying my message