For I have much joy and encouragement from [observing] your love, because you have cheered the hearts of the saints [i.e., God's holy people], brother.

not as a slave [only], but more than a slave, as a dearly loved brother. [He is that] to me especially, but how much more to you, both in a physical way [i.e., by continuing to serve as your slave] and in [the fellowship of] the Lord [i.e., now also as your brother in Christ].