I absolutely love this suggestion!
In fact, the only thing I would want to change is the Lvl 10 ability of Brand.
Right now it appears as though he inherited Bard's Black Arrow, however that arrow sunk together with Smaug, and no one ever dared to come near the place were the dragon's corpse rotted.
To add to that, it does not fit with the rest of his concept as a strong defensive melee-hero and it seems quite underwhelming for a Lvl 10 ability.
Instead, I would change his Lvl 7 ability to something akin to this:
Steadfast Ally
The target allied (Dwarven-)hero gets +30% Armour for a medium period of time. Should the hero die during that time, Brand has area of effect damage for 10 seconds.
This resembles how Brand stood side by side with Dáin, each of them fighting to the last. Of course it was Dáin who fought over Brands corpse, but had Dáin fallen first, Brand would surely have done the same.
It would also extend his tank-aspect onto other heroes, which seems less out-of-concept than a ranged single-target attack.
Thus, "Last Stand" would move to Level 10. To compensate for this, the ability could gain the added effect of Brand healing himself with each strike, to further reinforce the idea that he gets stronger if he is fighting in melee combat, and to show his great resilience.
Of course this are only ideas - anything except the Black Arrow would do, really.
Other than that, I am completley in favour of this suggestion!
Signed,
The Only True Witchking