According to Burke's peerage:

Sir Richard Waller, a gallant participator In the glories of Agincourt, who, in honour of having made prisoner the Duke of Orleans in that memorable conflict,  obtained from Henry V. the addition to his crest of a shield of the arms of the duke, pendant from a walnut-tree, which his descendants have ever since home. The French prince having been brought to Englaud, was confined at Groombridge. 

However 

Juliet Barker in her book Agincourt gives several examples of knights who augmented their coats of arms to commemorate having taken part in the battle.

One of these was Richard Waller of Groombridge in Kent where there is still a local legend that Charles d’Orléans, having been captured at Agincourt, was held for ransom and that this was so beneficial to Sir Richard that he was able to rebuild his house at Groombridge Place and contribute to the repairs at Speldhurst Church.  This story is celebrated in a stained glass window of St John’s Church, Groombridge which was built in the 17th Century as a chapel-of-ease.

The window contains the following arms and inscriptions:

left
arms of Charles d’Orléans
An Dni 1415

CHARLES DUKE OF ORLEANS WHO DURING HIS CAPTURE AT GROOMBRIDGE WAS A BENEFACTOR TO THE PARISH CHURCH

centre
arms of John Packer
An Dni 1625

TO THE GLORY OF GOD AND TO THE MEMORY OF JOHN PACKER OF GROOMBRIDGE PLACE ESQUIRE THE FOUNDER OF THIS CHAPEL

right
arms of Sir Richard Waller
An Dni 1415

SIR RICHARD WALLER KT OF GROOMBRIDGE BY WHOM CHARLES DUKE OF ORLEANS WAS RESCUED AT THE BATTLE OF AGINCOURT

Charles d’Orléans was to remain in captivity for 25 years. He was finally released in 1440 “speaking better English than French” according to one source.

However, the augmentation of the arms of Orleans were added at some time between the Heralds Visitations of 1592 and 1619 and were based on a confusion as Sir Richard Waller did not capture the duke of Orleans but was responsible for the custody of his younger brother, Jean count of Angoulême, who had been given as hostage to the duke of Clarence following the 1412 campaign and who was not released until 1445. Waller did serve, however, in 1415 as a man-at-arms in the retinue of William Bowys within the troops under Thomas, duke of Clarence, and also served in France on later occasions, but any role which he played in the capture of the duke of Orleans remains unsubstantiated.

Another example of the Waller coat of arms can be found above the main door of the Old Vicarage at Darrington in the former West Riding of Yorkshire. Here the arms of d’Orleans are impaled with Waller. The arms were placed on the building by Rev Dr Robert Burrow LLD (Vicar 1717-1754) who was married to Mary Waller. The motto “Considerate Lilia” is a quotation from Luke 12:27 but it is reference not only to the lilies of the field but also to the lilies or fleur de lys of France. By co-incidence, Darrington is only a three miles from Pontefract Castle where Charles d’Orleans spent some of his captivity and where he formed a friendship with the governor, Robert Waterton.