This coat of arms has been the symbol of the Franciscan for many centuries. The image of the two crossed arms, each with a nail wound in the hand, represent both Christ and St. Francis who received the Stigmata (the wounds of Christ) in his body two years before he died.
The cross behind the arms is actually the letter ‘T’ or ‘tau’ which is the last letter of the Hebrew alphabet.
Francis was very fond of the passage in the prophet Ezekiel (9:4) which refers to the faithful of God all being signed on the forehead with the letter ‘tau’. Francis often signed his letters with this symbol.
Pope Innocent III used this image from the prophet Ezekiel for the theme of the opening homily of the Fourth Lateran Council (1215). The Tau became a symbol from the Council for spiritual renewal in the Church. It is thought that Francis was present at this council and used the Tau from that moment on.
“For even while he [Francis] lived among men,
he imitated angelic purity
so that he was held up as an example
for those who would be perfect followers of Christ.
We are led to hold this firmly and devoutly
because of his ministry
to call men to weep and mourn,
to shave their heads, and to put on sackcloth,
and to mark with a Tau
the foreheads of men who moan and grieve,
signing them with the cross of penance
and clothing them with his habit,
which is in the form of a cross”.
St. Bonaventure, The Life of St. Francis, Prologue n.2 from E. Cousins (trans.) Bonaventure: The Soul’s Journey into God, The Tree of Life, The Life of St. Francis, Paulist Press, New York, 1978.