I do want to point out that any gift to Grimbeorn should also affect his bear form.
In the current setting I feel that Beorningers, including Grimbeorn, are not strong enough in their bear form, being too vulnerable to spears. If we increase the usefulness of the human form, the balance is completely lost.
I feel the concept should adequately consider the impact of Galadriel's gift on Grimbeorn's bear form as well, possibly increasing his unit support to fellow Beorningers. I absolutely support the idea of the axe, as it is the strongest aspect of the aggressive side of Grimbeorn's personality. On the other side, however, a certain blessing should be bestowed to the bear transformation, perhaps in the form of armour boost towards himself and surrounding Beorningers.