In his summary of medieval attitudes towards the disabled Henri-Jacques Striker wrote, "The mentality and attitudes were variable and ambiguous at the same time. Never truly excluded, for the disabled were always spiritually integrated; never integrated, for they were always on the social fringes." Henri-Jacques Stiker, A History of Disability trans. W. Sayers (Ann Arbor, MI: University of Michigan Press, 1999), 88.
Irina Metzler has written an interesting monograph on this subject and has critiqued Striker on a number of points. She notes that Striker was not terribly familiar with primary texts from the period and relied generally on secondary sources in his chronologically broad overview.
She notes that there was indeed a stigma in some contexts surrounding disability. Educational opportunities could be restricted for those with "grave" physical deformities and illnesses. Oxford for example had a statute in 1400 that barred students with these kinds of significant deformities and illnesses from pursuing degrees at all levels. Irina Metzler, Disability in Medieval Europe: Thinking About Physical Impairment During the High Middle Ages, c.1100–1400 (Taylor and Francis, 2006), 41-42.
She also notes that in the twelfth century there were a number of decrees that set a precedent for those wishing to enter the priesthood which restricted them from ascending to higher orders if they possessed "mutilations and serious blemishes." Ibid.
Metzler has investigated the underlying theological questions that surrounded infirmity and disability. In her view, while the Old Testament often testifies to direct causality between sin and deformity/illness/impairment that is not necessarily the case in the New Testament. As such, Latin Christian views towards deformity/illness/impairment could have a sense of moral judgment but this was not universally the case.
It has been speculated in earlier historiography that for medieval contemporaries deformity/illness/impairment was a sure sign of "God's displeasure" but Metzler believes this is not born out by the sources. In the vitae of St. Ambrose for example there are differing accounts; "in the earlier version, by Paulinus, a link between sin and illness was made, whereas the second version does not seem particularly interested in such a link." Ibid, 46.
All illness was in a sense the result of sin, but this sin was not necessarily the result of a transgression committed by a particular ill or disabled person. Illness was thought to be the result of Original Sin, and therefore the connection between the individual, their own sins, and the physical condition they possessed was rather murky. Indeed Metzler notes that illness or deformity could be kind of blessing given to a person by God that could allow them to grow in holiness. Ibid, 47.
In terms of battlefield injuries this question becomes more complicated. In the English context it appears that surgeons were paid for and provided by the sovereign to accompany armies on campaign but their services were largely restricted to nobles and officers. This is not uniformly agreed upon in the historiography, as some accounts of Crusading seem to indicate a more inclusive attitude. Nonetheless for those seeking care for grievous injuries the care could vary wildly depending upon your status. That said, when it came to medieval amputation the prospects were terrifying even with the best possible physician.
For example Henry V employed over a dozen surgeons at Agincourt to take care of the privileged (ibid, 118), however you as an eleventh century footman would likely not benefit from the expertise of these kinds of specialists in the treatment and healing of your wound, and could suffer more acute longterm health complications.
Metzler has pointed out that as a consequence of this common need for rudimentary healthcare in military service it was common from knights and other arms bearers to develop basic knowledge of some surgical techniques to assist themselves and their comrades.
For those honourably wounded in military service life could be difficult. Even for the affluent members of the warrior aristocracy one was dependent upon one's kinship network, family and friends for support, and needed to find some means of taking care of oneself. Knights could be compensated for their wounds sustained in service but these amounts would not last a lifetime. This could also be the case for mercenaries who had established formal guarantees with their employer but agreements were variable. While your injury was sustained as a footman in honourable service the callous realities of life still pressed upon you much as they would someone subject to a mill accident.
As a Latin Christian man it is possible you would express interest in spiritual or miraculous healing at a shrine. These places of pilgrimage were often famous for their powers to restore sight to the blind, or for having the ability to cure the lame, paralyzed, sick or mad. However to my knowledge the restoring of a limb to an amputee is not a miracle I have encountered in the literature. Perhaps someone else can provide a reference to the contrary.
Despite your injury you could possibly still serve in some capacity. Norman footmen used axes and swords light enough to be used with a single hand. If you could manage a way to strap a shield onto your forearm, provided it was of sufficient length after the amputation to do so, you could likely return to military service.