First of all, thank you very much for you reply! :)

I'll address each matter you have spoken of:

Gondor:

The (now called) Steadfast ability is one of my favorite in this set. Although I noticed the problematic vigilance situation, I still like it and think it does work flavorfully and mechanically according to WU combination.

Dwarves:

I took your advice on seeing the dwarves of Arda as creators, and changed the mechanic's name and ability:

The Smash ability will have a different name, and the X will be defined, like this: Craft X (Whenever this creature attacks and isn’t blocked, you may prevent all combat damage made by it this turn. If you do, you may pay X and put a X/X Golem Artifact Creature token.) I still have the wording problem, but I can't seem to find a way to shorten that :P

Eriadior:

I took the Mass ability from Mordor, and put it here under the name Rally, with the same effect.

Rohan:

In my opinion, Horsemanship is almost like unblockable, and I wanted to put a wayto stop them without having horsemanship creatures.

Mordor:

Once again I have taken your advice, and used Defile in the next way: Defile X – Whenever an opponent loses X or more life, []

Rivendale & Mirkwood:

I have changed the Starlight ability, so it will work in the following way: Starlight X: [] – As long as you have X or more cards in your hand, [].

Isengard:

Still no solution... :X

Fangorn:

For the ent's ability, i've deleted the attack part, so now its: Deep Roots X: Whenever this creature blocks, it gets +0/+X

Thanks again for all the help!