"The last of all the Bards was he,
Who sung of Border chivalry."
In the latter sentence, who evidently refers to Bards, which is called the antecedent of the relative.
The antecedent.
105. The antecedent of a pronoun is the noun, pronoun, or other word or expression, for which the pronoun stands. It usually precedes the pronoun.
Personal pronouns of the third person may have antecedents also, as they take the place usually of a word already used; as,—
The priest hath his fee who comes and shrives us.—Lowell
In this, both his and who have the antecedent priest.
The pronoun which may have its antecedent following, and the antecedent may be a word or a group of words, as will be shown in the remarks on which below.
Two kinds.
106. Relatives may be SIMPLE or INDEFINITE.