Dafydd's tenure of the see was uneventful. On 27 Oct. 1320 he had leave from the Crown to levy tolls at the ancient fair held at S. Asaph on 1 May (Cal. Chart. Rolls). It was about this time that the register of episcopal records known as ‘Llyfr Coch Asaph’ (The Red Book of Asaph) was compiled; the manuscript itself has disappeared, but its contents are known from three late transcripts in N.L.W. The bishop seems rarely to have left his diocese; he was, however, present at the consecration of Roger of Lichfield at Halesowen in June 1322. He was engaged in litigation in Dec. 1330 with the lord of Powys as to the churches of Meifod, Welshpool, and Guilsfield. In 1336, with the consent of the chapter, he appropriated the church of Nantglyn to improving the income of the ten vicars of the cathedral; from the act (confirmed by the king in 1341) it appears that the south transept (now the consistory court) had just been built. Legal proceedings were taken against the bishop in 1340-1 in an attempt to limit the temporal claims of the see; there was no attack upon his character (‘Flintshire Ministers Accounts,’ ed. D. L. Evans in Flints. Rec. Ser. No. 2, xxix-xxxiii).

Earlier writers were uncertain as to the year of Dafydd's death and thought that there was no new bishop until 1352. But the papal records show that (after a false start in April 1344) the news of his death in 1346 reached Avignon, enabling Clement VI to provide John Trevor I (q.v.) on 26 June to the vacant see (Cal. Papal Lett., iii, 235; Petitions i, 48).