oh so that was what he was trying to do, I wanted to warn him about his price but saw him doing dodgy things, so then I just tagged along: I just noticed the 10 energy (used to play diablo 2 and that game was way easier to cheat a trade until some later patch), demanded it changed, he did and cancelled the trade after I confirmed while saying thank you! and running away, I was clueless at what he had attempted but now I get thats his getaway line.

So he makes you add the shards so you aren't looking at the tiny warning icon that appears when something is changed on the trade window. And the fact you added shards would cancel the confirmation you have probably clicked after putting the money in. I believe the warning icon should be way bigger and perhaps appear in between the arrows that point at the trade, or better yet, have it diablo 2 style, with a big check that turns green when you confirm and turns red for a few seconds when something has been changed on the table.