The Subjunctive in ‘Relative Clauses of Characteristic’. The subjunctive is used in relative clauses to add nuance or subjective coloration. An adjective clause with the verb in the subjunctive would describe the antecedent not as particular, but generic or typic: the sort as would, not the one who is or was.
Because they characterize, rather than simply describe, such clauses are called Relative Clauses of Characteristic.
The subjunctive is used if the antecedent is indefinite (‘there are men who …’) or negated (‘there is no one who …’), or definite, but conceived as being ‘of such a sort’ (‘you are one who …’ = ‘you are the sort as would …’):
The Subjunctive in ‘Relative Clauses of Characteristic’.
The subjective coloration of the subjunctive in relative clauses may impart to the clause meaning equivalent to one of several adverbial categories:
Notice that the relative clause of characteristic may often be translated by an English infinitive phrase used adjectivally: ‘a man to fear’ = ‘a man such as one would fear’ = virum quem metuās.