First comment is: Drop that ruddy horblower! It's of no use and no help.
Second thought is that the 2-handers are slightly too small, switch a shield company into a 2-hander company (personally, I would have it as three formations as dwarfs can take the hits - if you go with two formations go for a 3c and a 4c to keep it balanced. Might be worth considering having the 2-handers as the 4c though because they're easier to kill and have less attacks).
Third: I agree that the Ent is a little... lathargic in this list. You would need at least two to have them be useful (in any army), otherwise it dies quickly with no gain. You could always drop it and replace it with stuff (first thoughts regarding that are to drop the captain [overpirced, IMO, without enough gain to be worth it when an Epic hero will do better] and replace with a King's Champion if you want a monster).
Fourth: Always try to use up spare points. You have 15 spare - if you had 15 spare, I'd say take a hornblower, but you already have one (which I said to drop) - instead, take a third company of rangers (instead of the hornblower and this assumes you drop the ent: gotta keep the % in check).
So, my comments that try to change the list as little as possible, turn it into the following:
Gimli
4c of Warriors (Shields or 2Hs, your choice, but I'd suggest 2Hs here and shields in the 3c)
3c of Warriors (2Hs or Shields - preferably shields)
3c of Rangers
King's Champion
Dwarf Ballista
800pts on the dot.
It keeps the same basic premise of the list, makes it more thematic, strengthens the units and Gimli can always be the counter to the -1F of the 2-handers if need be and with his and the KC's Inspiring Hero rules, only the Rangers don't benefit from increased Courage anyway.
Damnit, just realised that your rangers are likely dwarf rangers: if so, give them bows or don't bother with them - most others can do their job better.
Gimli
4c of Warriors (Shields or 2Hs, your choice, but I'd suggest 2Hs here and shields in the 3c)
3c of Warriors (2Hs or Shields - preferably shields)
King's Champion
Dwarf Ballista
700pts and thusly some room to spare. Another company of Warriors, a Banner Bearer and a Shieldbearer can fill that up or a company of warriors and another ballista or 2 companies of warriors (or rangers with bows) and a hornblower (if desperate for it
), leaving you 5 points spare.
the rolls...both 5's, add the +1 and they became 6's. d6+4 hits, the rolls? yeah...both 6's, so 10 hits from each ballista at str8 on d7 (need 4+). The following rolls 
...ALL 4+, did 20 wounds on his 5c of Knights of Amroth. 
Game. (we kinda of just looked at each other...blinked...and started to redeploy for another game)....
Game.
If you still has 15pts floating about, you may as well spend it on another hornblower (then you have two with the extra inch or two 
).
