First of all, i know that there is a thread for new mythics, but what i want to say is not going to fit as a comment.
Let's discuss the new mythics. First of all, let's take rogue.

~rogues bow procs-
It will create a Bush,wich will first of all heal the rogue.
Other things the Bush will do is damage the enemies, and remove stuns and snares.
Also, every time you fire the bow you will get 10% of the damage you did as health To yourself.

Let's move on to the warrior.

~warriors bulwark (wtf is that XD) procs~
It will create a spirit, wich will heal allies,boost their primary stat by 20,
and also shield the player that is under the effect.
How much it will shield, or if it will remove damage completely, we do not know.

Now, last but not least, sorcerer.

~sorcerers Gun procs~
They will have a chance to basically stun the opponents.
Also it will remove dodge and a little bit of armor.
In addition, it have a extra that looks like the rogues extra...
It will recieve 20% of the damage dealed as mana.

Now, you are propably thinking "oh, these look so awesome!"
However, the mage one have two big problems.
1. The rogues proc is basically perfectly created to remove the mages entire proc.
2. Why on nearth would a mage need alot of extra mana?

However, the rogue weapon is Perfect for pvp, and the warrior one seems to be god in both pve and pvp.
After thinking about this for a few minutes i realised 3 things.
1. mages can now kill warriors with a little luck.
2. rogues can now kill mages with a little luck.
3. Everyone will die anyway, because we have too weak amulets/rings to survive a crit from a rogue.

So, unless you are a rogue with a mythic bow, or a EXTREMELY Skilled mage/warrior,
you should propably stay out of pvp.
Any thoughts/things i missed? Please feel free to agree or disagree
Also, we can't know anything until we see these weapons in the game, these are just my thoughts and predictions, i might be 100% wrong!