In the context of bringing the gospel to the gentiles, Nephi notes that they receive no less than have the Jews. The Spirit will also manifest Jesus to them. The gentiles may also experience mighty miracles, signs, and wonders, according to their faith. Nephi, as a Jew and a member of the covenant from birth, certainly understands that the God of Israel has at times manifested his power to them through miracles, signs and wonders. This spiritual history of the special relationship of the house of Israel and their God is the heritage of the covenant.
Nephi is very explicitly telling the gentiles that they too will be able to receive these same benefits in the future (though they have been excluded from them in the past as they were not part of the covenant). Nephi makes explicit the connection between the future mission of the Spirit to work through faith rather than the covenant.
This is an important statement, not only for the future gentile populations, but perhaps for the social conditions Nephi was dealing with. For an analysis of this possibility, see the discussion of 2 Nephi 26:33 below.