Hi ! ( Seeker 103 NV 3rd) here i ll say some tips to kill Sins !
1. When you fight to a sin that is in stealth you should use the skill to see ppl in stealth or when he Atacks from stealth Domain, Faith, or Expel and then you run with Sage Unffeter and use Blade Affinity to kill the sin b:victory
2. always try to stay away from the sins because they always want to stun us so you should run ! with sage unffter and atack you can try to stun with Voidstep and atack too.
3. Seekers have a skill called Rewinding Gesture very useful to reset Unfetter and Voidstep b:thanks
4. other thing that seekers can do is use the skill called Edged Blur very useful to kill sins, Archangels of Justice are very good too you can use the pets and skills at the same time to kill very fast ppl
5. usually i kill sins with Heartseeker Ion Spike Battosai Arme Nier and Gemini Slash with Blade Affinity ! -chan ! b:victory Sage !
6.Sage Quid Pro Quo is very nice too you can transfer some debuffs for example when a sin paralyze you , you can transfer it and then atack .
7. pvp pots and charm not necessary :P
sorry for my english i hope the seekers that read my post understand me tips