The older Reformed meant justifying grace only
Thesis XVII. Indeed, I think that even those older writers who seem to disagree do not really disagree. When they argue against the scholastics that grace is not a habit infused into the soul, they are plainly dealing with justifying grace.
So their meaning is not, without qualification, that God infuses no habits of virtue into believers' souls through the Holy Spirit, or that such habits are never called grace. They mean only that the grace by which scripture says we are saved and justified does not consist in those holy habits at all, and that this grace means God's mercy and goodwill alone.
The proof is this. At times they deny that the grace by which we are saved, justified and even regenerated is a habit and infused quality, and they also deny that it is anything created and inhering in us, as we reported of Polanus above. Yet Polanus himself, in the same chapter, grants that there is an inhering grace. This, he says, is faith and also the grace of conversion and regeneration, which people call the grace of Christ the Redeemer, and likewise Christian grace.
So when he denies that regenerating grace is anything created and inhering in us, he is speaking only of the efficient and impelling cause of our regeneration, not of what the scholastics call its formal cause.
Latin
XVII. Imo illos ipsos ex vetustioribus qui dissentire videntur, revera non dissentire puto. Quum enim contra Scholasticos contendunt gratiam non esse habitum in animam infusum, manifeste de gratia justificante agunt. Itaque mens eorum simpliciter non est, nullos habitus virtutum in fidelium animas a Deo per Spiritum sanctum infundi, & ejusmodi habitus nullibi gratiae nomine designari: sed hoc tantum, gratiam per quam in scripturis dicimur servari & justificari, in sanctis istis habitibus nullo modo consistere: sed per gratiam istam unice significari Dei misericordiam & benevolentiam. Cujus rei argumentum est, quod aliquando gratiam qua servamur, justificamur, imo & regeneramur, non tantum negant esse habitum & qualitatem infusam, sed quicquam in nobis creatum & inhaerens, uti de Polano supra retulimus. Et tamen idem Polanus in eodem capite agnoscit esse quandam gratiam inhaerentem, quae, inquit, est tum fides, tum gratia conversionis & regenerationis, quam gratiam Christi Redemptoris, item gratiam Christianam vocant. Adeoque quum negat gratiam regenerantem esse quicquam in nobis creatum & inhaerens, loquitur tantum de causa efficiente & impulsiva regenerationis nostrae, non de causa quam vocant Scholastici formalem.