The seven sacraments of the Holy Church are these: baptism; confirmation; the Eucharist; the penitence that one does for his sins; the orders that the bishop makes when he ordains priests, deacons, and subdeacons; matrimony; and anointing of the sick. By means of these seven sacraments shall we be saved. And the sacrament of Chivalry is obliged to honour and comply with these seven sacraments, and it therefore pertains to every knight to know his office in such matters as he is obliged to.
[Ramon Llull, The Book of the Order of Chivalry, Noel Fallows, tr., The Boydell Press (Rochester, NY: 2013), p. 64.]
Llull is quite serious in calling chivalry or knighthood a sacrament. He does make a distinction (as is clear here) between chivalry and the salvific sacraments of the Church. But it's an essential part of his argument throughout the book that there is an analogy between the temporal Order of Chivalry and the spiritual Order of Clergy. Clerics (which would be minor orders) and knights are the two great orders of service, the clerics serving spiritually and the knights serving temporally. Not all clerics would have full-blown holy orders, and there is probably a closer connection between knighthood and minor orders (ordained lector, subdeacon etc.) than between knighthood and the major orders (deacon, priest, bishop), but the word used in Latin, ordo, would just be used for all of them. In Latin, you don't generally say something like 'the sacrament of holy orders', you just say 'the sacrament of Order'. Thus Bl. Ramon conceives of receiving knighthood as a form of being ordained -- you receive Order of a particular kind -- and receiving spiritual orders, conversely, as receiving a kind of spiritual knighthood. Clerics, whether minor or major, are inducted into this spiritual knighthood; like temporal knights they bring peace to society, but rather than the peace of justice through the sword, it is the peace of mercy and grace through the sacraments.
Knighthood, however, is not holy orders; it is a temporal office and not a sacrament that is either directly or indirectly necessary for salvation. The sacrament of chivalry is a sacrament (or sacramental, as we would usually say today) for laity. What has happened in the priesthood, if I understand Llull's view correctly, is that God has taken something we naturally do -- we give people Order so as to structure society in ways that allow for peace and justice -- and put forward a higher version of it (an Order that gives grace in and of itself); after which Christian knighthood becomes possible. Such Christian knighthood involves bringing one's temporal Order into alignment, value-wise, with the kind of divine and spiritual Order in the sacraments of the Church.
The Book of the Order of Chivalry, which Llull wrote at some point in the 1270s, was an extremely popular work through the rest of the Middle Ages and into the Renaissance, and thus was a major influence on how knighthood was conceived throughout the period.
