Aham Brahmasmi or I am Brahman, is the eternal Reality so the Self is ultimately Brahman. This truth confines one to an ashram away from worldly matters as sadhus oblivious to ones physical needs as desires and ego vanishes in the Brahman state where there is no mind or mindfulness thoughts. It is serenity, biss and love for all things.
For a housholder with duties even knowing this he or she cannot cut oneself off from worldly affairs and so has to find the optimal framework of religion to perform his dharma and hnd for a Vishista advaitist God exists to live in bhakti of devotion to. When the worldly chores are over the person can return to his Self (Brahman) in ananda of peace and tranquillity of mind. So the Vishista-advaitin has these two dimensions to his existence known as the vyvaharika (worldly) and paramarthika (heavenly) states of being which he can swtich between for dharmic purposes.
Dharmayudha is the dharma in vyvaharika whereas dharmayoga is the dharma in paramarthika.