That wording is in some of the Eucharistic Prayers as an option to be said where a deceased is being remembered. It doesn't mean the person was martyred. It calls to mind the person's baptism, which is a union with Christ's death on the cross and in his resurrection.
From the CCC:
1214 This sacrament is called Baptism, after the central rite by which it is carried out: to baptize (Greek baptizein) means to "plunge" or "immerse"; the "plunge" into the water symbolizes the catechumen's burial into Christ's death, from which he rises up by resurrection with him, as "a new creature."