Complex sentence: The Pecwae are weak and preyed upon by other races, and the Trevenici protect them, inexchange the Pecwae offer magical aid and healing to the Trevenici who shun magic.
Split into simpler sentences: The Pecwae are weak and preyed upon by other races, and the Trevenici protect them. In exchange the Pecwae offer magical aid and healing to the Trevenici who shun magic.