大毘盧遮那成佛經疏 3.31

3.31

「兼綜眾藝」者，謂妙善世間種種伎藝也，謂聲論、因論、十八明處、六十四能、算數方藥、觀相工巧之類。緣漫荼羅所要皆不假於人，則造次施為無闕乏之過，然後堪作阿闍梨。復次行如是法中，盡與實相不相違背，名為妙善眾藝。復次於一切總持、三昧門、道品、諸度、四辨、四攝、力、無畏等皆得善巧，則能隨意造作祕密漫荼羅，名為妙善眾藝也。

Regarding "comprehensively proficient in diverse arts": this means being wonderfully skilled in the various arts and crafts of the mundane world, namely grammar, logic, the eighteen fields of knowledge, the sixty-four arts, mathematics, medicine, physiognomy, craftsmanship, and the like. Having everything required for the maṇḍala without relying on others, one can execute it readily without flaws of deficiency, and only then is one fit to be an ācārya. Furthermore, among practicing such dharmas, doing so entirely without contradicting the dharmatā is termed wonderfully skilled in diverse arts. Furthermore, being skillful in all dhāraṇīs, samādhi gateways, factors of awakening, perfections, four unimpeded knowledges, four means of embrace, powers, fearlessnesses, and so forth, so that one can create the secret maṇḍala as one wills, is termed wonderfully skilled in diverse arts.