Hi Rhys, a few comments:
I assume this is an OT build? If not this build will not generate threat/second nearly as fast as a regular prot build (no imp sunder, focused rage, shield slam... and perhaps devastate should be mentioned as lacking).
This build lacks cruelty, which does affect both dps and also reduces the treat you generate as a tank (though that pales in comparison to the lost dps).
Rend is completely worthless, and you want as much parry as you can get (it's both defensive and offensive in nature since it blocks attacks and speeds up your attacks). Never spec imp rend past like level 30.
One problem with this build is that mortal strike and one handed weapon specialization don't mix. I wouldn't bother with one handed weapon specialization if you are getting MS. MS is all about getting the biggest slowest weapon you can find to maximize damage.
If you are going to take MS with a tanking build, you might as well take 3/3 in tactical mastery in order to get MS to generate more threat when tanking (they changed this relatively recently).
I wouldn't bother with imp shield bash... unless you plan to pvp as prot specced.
If you are going that deep into prot, imp sunder armor is never a bad thing.
If you are just going to go for a OT spec, maybe just do something like this:
http://www.wowhead.com/?talent=LVMcdNioM0zZVZcAtoI0z
If you are going to try for a MT spec with some dps added in a common dps/tanking build is something like this:
http://www.wowhead.com/?talent=LA0czhbZcZzEtoI0zcxsu
Just some thoughts.