Sir Philip de Stanton, Lord of Stanton

Somebody needs to make up their mind: was he a Templar or a Hospitaller? They were two different military orders, and you could not belong to both simultaneously. (Nor could you be married - though you could be a widower.)

By the 13th century, the Templars were based on Cyprus, but the Hospitallers retained toeholds in the Middle East until 1291.

Malta does not enter the picture until 1530, when Emperor Charles V gave it to the Hospitallers after they had been forced off Rhodes (1522).

There are numerous places in England identified as "Stanton", but apparently none of them were held by a Philip Stanton in the early to middle 13th century.

No evidence whatsoever for a marriage to Joan, daughter of William (the) Marshal - in fact she predeceased her only known husband, Warin de Munchesney. (Maybe check the descendants of John Marshal?)