Runeglave enchant item missing text

If you look up the new Runeglaive item doesn't have any text explaining the sheen on-hit affect it has. Only the in game store has the text or actual item has it. If you use the item sets or mouse over someone else-es build it doesn't have anything for it.

I was in a bot game testing something and was trying to help the friendly Ezreal know that he shouldn't build two sheen items. A bit hard when it's not even in the text for the item to show him/her.