Eagles - at least of the species Johann uses - are startlingly large birds, big enough to not have the "diminutive size" power.  While the exact details vary slightly with species, Johann's eagle forms have wingspans ranging from six-and-a-half to nine and a half feet (more for the sea eagle, less for the two forest-adapted species), and weigh roughly 30 / 25 pounds for female / male eagle forms, respectively.
And yes, these sizes are somewhat larger than those seen in wild eagles; Johann doesn't care - and they're not entirely unreasonable numbers for an eagle raised in captivity with no flaws in its diet.  (See also Haast's Eagle, an extinct species that's actually slightly larger than the forms Johann currently uses.)  This does occasionally cause issues with packs of alert bird-watchers, though.  (Though that may also be due to his choice of species; outside of south america, the philippines, and the northern pacific rim, all three species are... a bit out of place.)

-1 Echoes of the Beast (reduce distance related penalties to vision by one)
-1 Wings
-1 Claws
-4 Supernatural Speed
-4 Supernatural Recovery
+3 Catch
+0 Cargo Capacity: -2 might skill for purposes of carrying things while in flight.  Even a thirty pound eagle has its limits.
-1 Eagle Eyes: reduce distance-related penalties to vision by two; this stacks with echoes for a total of three.
-1 Grasping Talons: use fists skill instead of might when grappling - though the eagle must still use might if it wishes to prevent its target from moving.  (I.e., just because there's an eagle attached to your arm doesn't mean you can't run around; you'll just take the eagle with you, that's all.)

(unspent: +1)
+6: athletics, alertness
+5: investigation, fists
+4: lore, scholarship
+3: conviction, presence, stealth
+2: discipline, endurance, empathy, rapport
+1: survival, performance, might, deceit

details on individual forms:
one each male and female of the following three species:
Philippine Eagle
Harpy Eagle
Stellar's Sea Eagle