While he was as qualified as any, Francis chose to remain a deacon and not progress to the priesthood.
St. Francis of Assisi, being the founder of the Franciscans, is commonly thought to have been a priest. However, he never was, and only progressed to the Order of Deacons.
Throughout Francis’ life he had a great reverence for priests. In Thomas of Celano’s biography, it is written that Francis frequently kissed the hands of priests he met “with great faith,” honoring the special consecration they received on their hands on the day of their ordination. Francis had a special devotion to the Holy Eucharist and highly revered those hands that daily touched the Sacred Host.
It is recorded that Francis often said, “If I saw an Angel and a priest, I would bend my knee first to the priest and then to the Angel.” This again reflected the special respect Francis had for ordained priests. Regardless of their moral character, Francis held them in high esteem as he knew they were set-apart by God for a special purpose.
To help understand his reverence for the priesthood, the Catholic Encyclopedia summarizes Francis’ love of the Eucharist and how that may have led to his decision not to become a priest.
The mystery of the Holy Eucharist, being an extension of the Passion, held a preponderant place in the life of Francis, and he had nothing more at heart than all that concerned the cultus of the Blessed Sacrament. Hence we not only hear of Francis conjuring the clergy to show befitting respect for everything connected with the Sacrifice of the Mass, but we also see him sweeping out poor churches, questing sacred vessels for them, and providing them with altar-breads made by himself. So great, indeed, was Francis’s reverence for the priesthood, because of its relation to the Adorable Sacrament, that in his humility he never dared to aspire to that dignity.
While St. Francis was as qualified as any to be ordained a priest, he never was, feeling unworthy to ascend the altar steps and call upon God’s power to bring about the miracle of the Holy Eucharist.