Mononoke Hime, Bounen no Xamdou Recommendations
The world and character designs of Xam'd are all very Ghibliesque. Akiyuki may have been created drawing some inspiration from Ashitaka; each character is forced to accept his fate after absorbing a dangerous and ancient power into his forearm.
Both feature a lost boy searching for his purpose, where both of them have received powers that they didn't ask for. They both meet a mysterious girl who helps them throughout their journey but also acts as the deuteragonist/protagonist.
Both series involve themes of dying nature and tackles the problem of human interaction and nature (In Mononoke, humans tearing down forests; in Xam'd, humans abusing shamans for personal gain.) Symbolism is also integrated in both series, some symbols being "rebirth" and "hope." Both series also feature great artwork, animation, and soundtracks.