Today is the anniversary of the violent death of Bl. Infante Don Sancho of Aragon, Archbishop of Toledo, following the battle of Martos in 1275. The life of the twenty five year old Sancho, Archbishop since he was sixteen - now those were the days - is outlined by Wikipedia at Sancho of Aragon (archbishop of Toledo) The campaign on which he died is recounted at Battle of Martos
A tangible link with Bl. Sancho is one of his chasubles which survives in the cathedral at Toledo. Made of silk and cloth of gold is a spectacular display of the arms of Castile and Leon together with those of Aragon and Sicily.
Image: New Liturgical Movement
This is not the only such example of such an heraldic textile from thirteenth century Spain. In the collections at the Royal Palace in Madrid is a fragment from the emblazoned mantle of King Ferdinand III of Castile and Leon ( 1217/30-52 ) who was later canonised in 1671 as St Ferdinand. It can be seen here
A well known manuscript illumination shows King Alfonso X ( 1252-84 ) in similar garb:
As to how such a chasuble should - and indeed should not be worn - I recommend the following article by Shawn Tribe on the Liturgical Arts Journal website from 2018 which reproduces an illustrated 1957 article on the “dos and don’ts” of vesting in a conical chasuble and which can be seen at Sacristy Tips: How To Correctly Wear a Conical Chasuble