I started tanking not long ago and i reading alot of different things some ppl are saying go all mastery other to avoidance.And a few day u need hit other say u not this is my armory can anyone tell me if i doing anything wrong?
I'm not expert on DK tanks so take the following with a pinch of salt.
You want both Mastery and avoidance, I wouldn't worry too much about threat stats; while missing a Deathstrike is nasty it generally should not kill you and a dodge/parry will refund the runes anway so you can just try again next GCD, you should be able to produce enough threat without any hit or expertise so i wouldn't gem either of those or reforge to them either.
The balance of Mastery versus Avoidance is quite dynamic if you're tanking multiple adds you want to favour avoidance , but for single target tanking you favour mastery. However whatever you do you want to keep your avoidance ratings balanced when you're fully buffed, Horn of winter adds like hundred and something parry rating and Kings/MOTW adds about the same again, so even though at present in your unbuffed state youe parry and dodge ratings are pnly ~50 ratings apart when buffed that will jump to about 200 ratings apart.
I would also rethink talents, you want to get second point in Scent of Blood, and You don't necassarily need Abomination's Might or Crimson Scourge in the blood tree. AM can be provided by other classes (MM hunters, Enh shammied, Paladins) further more Tanks don't scale all that well with AP as we tend to get alot of it from vengeance, and Morbidity in the Unholy tree is better for AoE than Crimson scourge.
I personally favour Virulence over Unholy command as I don't find I need that many taunts and a 20% harder hitting diseases is quite nice. I also don't find Icy reach all that useful, I only Ice touch once per minute on most boss fights.
you could however keep Icy reach, drop 3 points into Runic Power Mastery and pick up Lichborne, combined with the Glyph of Death coul this can give you a powerful self healing setup as you pop LB and then Death coil yourself.
As teng said, mastery for single target and avoidance for multiple targets if you are able to do multiple gearsets. I personally have gone mastery for my "main" tank set.
Hit and expertise are nice to have but not required as vengance will allow you to hold aggro 99% of the time unless there is someone that severely outgears you which at your gear level is probably full FL gear.
I kinda like the idea of using that DPS trinket to tank for a little bump during DPS races. Otherwise, it's definitely time for a new weapon. Also, I'd take the point out of icy reach in favor of finishing out Scent of Blood since Icy Touch isn't the monster aggro it used to be and you should be pulling with DnD or Outbreak anyway. Depending on what you run most often as a tank, if you can't make two sets (trash and boss) I'd try to keep EVERYTHING as high as possible. Myself, I reforge everything that already has mastery to dodge, and pieces with Dodge to mastery. Reforging out of the threat stats of old (Hit, Exp, etc.) is awesome. Don't even bother enchanting for it, gemming for it, anything of that nature. Also, I get my parry from strength and reforge out of it to keep a nice balance.
If you plan on being a BAMF tank, since you have 525 skinning, stack leather of all levels beyond belief over a few days and trade skinning out for LW. Best wrist enchants in Azeroth, plus being able to make your pants enchants for both specs. Plus you can use the lower level junk from LW to level enchanting on an alt, or gear it depending on the class! I think I might use that idea myself on my shaman, actually.