Please answer me !!

Can I use Wizard to buy Assassin competition set and trade with Assassin on another account?
how can I send competition points to other character ( diff acc )

you cant buy with wizz set for sin,because if you do that ,assasin set will be Bound ...and you need soul infuse bound items,then remove soul infuse to get rid of that bound,,but you like wizz Can't soul infuse other class set..... understand?
you can soul infuse only your class set.. [like how you can only enhance your class weapon]

Also if you are consume competition pills and have competition points on your wizz - you cant send that points to any other acc,or cant send to other char...also that points is not count in 1 account for all characters...so only for you

Can I make another Sin on Wiz's acc then trade PVP set to the Sin on another acc?

well you can,but when you make assasin in that wizz account,that competition points you not share with new character in that account...so what is point make sin in wizz account then trade gears to other your sin?

so again... when you have competition points,that is only for that 1 character...if you want sin class,and want pvp gear,you need earn again pills to use and get points to buy gear for sin...... only competition pills can be traded,but if you consume pills- you get points= points cant share

does it allow us to trade pvp weapons? sorry for asking too much !

you can trade your class weapon only...it is same if you buy for assasin weapon and you are wizzard ,how you will soul infuse that weapon for remove bound stuff if Npc not allow you soul infusion because that is not your class weapon??