If by black mailing him you mean telling him that he can not multiaccount then yeah... blackmail.
Since these two are my PMs to him:
Helmet
Hey man, as you do not have a forum account i will PM you from here.
This dude: http://forum.c-rpg.net/index.php/topic,25952
Is really sad that you bought his helmet for super cheap as he intended to give it to someone else to heirloom it.
Please be nice and return it to him.
Best way would be clicking the blue banner next to the Battle button and register on the forum, then answer in the thread.
Would be awesome, appreciate fair players
Have fun!
In between he answered "I SOLD IT!"
Re: Helmet
Well, are you cool with us reverting those trades?
Also check the PM on your other account...
That PM on the other account was me telling him that he can not use two accounts and was completely unrelated to the case.
Just happened that I saw him multiaccounting while investigating the transaction the thread is about.
So get your facts right before you call someone out for abusing his position.
As soon as i get his answer to the second PM I will contact the buyer and get this sorted out.