Might can help you but some guys always look to put as much as they can...
Anyway you are just fine as you are... If you enter a tournament good luck...

remove bolt thrower, give imrahil a horse n lance and take a captain on foot
drop the KoMT and take mounted swans.

Basically I win alot with

Imrahil mounted lance
captain mounted lance or foot
Beregond (cheap might but fits)
4 mounted swans
Maxed out combos of swan on foot, ranger with spear, men at arms.
Try and always have slighlty more swans on foot than men at arms
eg.
13 swans on foot
10 Rangers
7 men at arms.

1st: Why mounted swans, ? The bolt thrower and swans on foot are pretty good at taking out elites and such. The KoMT were ment to weak the enemy in a pretty big cavalry charge. Beregrond was meant to make sure they'll charge.
2nd: Giving imrahil a horse ruins 'DA for Gondor', because only 5 models will be under influence. And those models again cost about 40% of the points.
3d: I do have slightly more swans on foot than MaA and RoG, to fill in gaps and guard the flanks.

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We must forgive our enemies...
But not before they are hanged

1 and 2) mounted swans with imrahil don't go riding off but hang around BEHIND your pike block as a counter attacking force.
It is inevitable the enemy will get round the edges eventually but with these guys behind they will get slaughtered.

I understand what you're saying, but the main idea is to deploy the army on a table edge or corner, so they won't get flanked easily.

_________________
We must forgive our enemies...
But not before they are hanged

recent tournie missions rarely let you be so cunning... also its the good old "wrap round and try and bum saruman" trick on occasion,

This is a really good list. Though i would really advise getting Imrahil a horse, he's nigh on unstoppable when he's mounted. And when the battle dies down he will be a huge asset being able make his stand fast most affective wherever on the board, not to mention his banner rule.

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So do all who live to see such times. . .

Yes, maybe... But what should I drop then ?

_________________
We must forgive our enemies...
But not before they are hanged

I would drop three swan knights on foot, use the points saved from one to give imrahil a horse, and the points from the other two on buying more crew for your bow (you could probably afford three crew if you count your spare points along with those made from giving up two knights)

As for anti magic on imrahil, you have the bolt thrower, unless if your facing shadow lord most people will keep their nazgul etc, well out of the way of your bolt thrower.