why these unbind scroll(event) set up to "can't not be exchaged"?

it is so rediculous one of our clan members got a unbind scroll-s grade from snake today, first i was happy cuz i have a bound arcana mace, i wanted to buy the scroll from him, he said to me :give me ur weapon and i would help u.
i think he is a newbie so he doesn't know about bound items can't be exchanged. then i told him about this. he showed to me this scroll, ah, this scroll(event) can't not be exchanged too!(╬▼皿▼）
both he and i were able neither to cry nor to laugh. i have the bound items of s grade but not him, he keeps the scroll and can't do anything though.

 

are you sure? i got unbind weapon r grade and sell it at ah with no problem... s grade should be no different

 

it is different. s - are event type.

 

y, only s grade cant not be exchanged, the other one in our clan got a unbind armor (r),this one can be exchanged and sell in ah. the man who keeps the scroll (s) doesnt have any bound items of s grade.....

 

i had exact same thoughts...and there is no other way of getting them. too bad the event is over.