I appreciate it has been a while since this thread was active however when I noticed it I found the idea behind it interesting. While Boromir is by no means a bad hero, I do find that compared to the other heroes that share his role he seems a bit stale in what he has available to him.
So keeping the idea proposed here (him using his horn and shield as the basis) I thought he might be interesting if he worked on a system similar to Dunmarth / Faramir, being able to toggle between two separate forms, and had abilities dependent on them and here's what I came up with. I appreciate it might not be possible to implement these, nor might the suggestions be good ones, but I feel it would make Boromir a bit more versatile and fun to use at the same time.
Please note that Boromir's stats would not change to accommodate these, only his visuals (his free arm) would be majorly effected.
Captain / Defender Toggle
Boromir switches between the Horn of Gondor and his Shield. Passive: If Boromir dies, he will continue to fight for a short time, knocking back enemies.
Level 3: Horn of Gondor (With Horn equipped)
Same as current
Level 3: Guardian (With Shield equipped)
Boromir targets an allied hero, shielding them for 30 seconds. During this time, Boromir cannot be controlled, but will circle around the target, knocking back enemies, and absorbing all damage that would be dealt to them.
Level 5: Son of Gondor
Boromir dons the armour of Gondor, gaining enhanced defence values. Allied infantry units near Boromir gain +25% damage if equipped with his horn, or +25% armour, if equipped with his shield.
Level 7: Silver Call (With Horn equipped)
Boromir sounds the silver trumpets of Gondor, for 30 seconds, Boromir, and all other allied units on the map will gain 25% movement speed when passing allied buildings, or when near to Boromir. Captain / Defender toggle is disabled while active.
Level 7: Brave Resistance (With Shield equipped)
Same as current. Captain / Defender toggle is disabled while active.
Level 10: Veterans of Gondor
Same as current