Above is a diagram (from this site) of a knight's plate armor, as well as that of his horse.  Since there aren't horses in Redwall - or at least, not any sentient ones, and not in any of the books except Redwall - we'll ignore the horse armor and just concentrate on that of the knight.  To learn how the armor was put on, go here.  Following are definitions of the various pieces of armor, taken from this site.

Ailette -- A flat plate of leather or parchment which tied to the point of the shoulder. Worn between 1250-1350 to display the owner's coat of arms.
Aketon -- A padded and quilted garment, usually of linen, worn under or instead of plate or mail.
Armet -- Fifteenth century helmet of Italian origin consisting a skull, two hinged cheek pieces which lock at the front, and a visor.
Arming doublet -- Quilted garment worn under armor from the early fifteenth century, equipped with points to attach mail gussets and pieces of armor.
Arming points -- Ties (usually of flax or twine) by which armor was secured in place.
Aventail -- A curtain of mail attached by means of staples (vervelles) around the base of a helmet (especially the basinet), and covering the shoulders. Also called camail (a French term).
Back Plate -- Plate armor protecting the back half of the torso.
  -- A high bevor with a falling lame containing eyeslits; used in Spain.
Barbut -- Also called barbute, barbuta. An open-faced shoulder-length Italian helmet, made in one piece, with a T-shaped face opening. Barbuta is the Italian term.
Bard -- A full horse armor, which could include a shaffron, crinet, peytral, crupper and flanchards.
Basinet -- Also called bascinet, basinet. An open-faced helmet with a globular or conical skull enclosing the sides of the face and neck. Usually worn with and aventail, and occasionally a visor.
Bellows Visor -- A modern term for a visor with horizontal ridges, such as on 'Maximilian' German fluted armors of the early sixteenth century.
Besagew -- Defensive circular plate suspended over the wearer's armpit.
Bevor -- Also called bavier or buffe. A chin-shaped defense for the lower face, incorporating a gorget plate. The buffe was an early sixteenth century variant, worn strapped to an open-faced helmet such as the burgonet.
Birnie -- Also called byrnie. A mail shirt. See also hauberk.
Bishop's Mantle -- Modern term for the cape of mail worn (largely in Germany) in the early sixteenth century.
Blueing -- An oxidized blue surface on plate armor, produced through heat treatment.
Bouche -- The notch cut in the top (dexter) corner of a shield, to rest the lance when jousting.
Bracer -- Early fourteenth century form of defense for the lower arm; also a term for an archer's arm guard to protect the forearm from the bowstring.
Breast Plate -- Armor that protects the front of the torso.
Breaths -- Holes or slits in the visor of a helmet or the lames of a falling buff or bevor, for ventilation; also usually permitting a degree of etra vision.
Brigandine -- A flexible body defense consisting of a large number of metal plates riveted inside a cloth covering.
Buckler -- Small round shield carried by infantry.
Buffe -- see bevor and falling buffe.
Burgonet -- A light, open-faced helmet popular in the sixteenth century as an alternative to the close-helmet for light cavalry. It was usually furnished with a peak over the brow, a combed skull, and hinged ear pieces. The face opening could be closed with the addition of a falling buffe.
Byrnie -- see birnie.
Cabacete -- A type of Spanish war hat (popular throughout fifteenth century Europe) with a turned-down brim and an almond-shaped skull ending in a stalk. See also morion.
Cabasset -- see also Cabacete and Morion.
Camail -- see aventail
Cannon -- Individual plate armor defense, of tubular form, for the upper and lower arm. See also vambrace and rerebrace.
Case-hardening -- A method (described in the twelfth century treatise 'De Diversis Atibus' by Theophilus the Monk) for surface hardening wrought iron (or low carbon steel) by packing it in charcoal or other organic material and heating it for hours above 900 degrees Celsius.
Casque, casquetal -- A light open helmet; usually late fifteeth to mid-sixteenth century helmets of 'antique' form, such as Italian parade 'casques' of the mid-sixteenth century, embossed with grotesques or fashioned in the classical style. These were often similiar in shape to the burgonet.
Celata -- Open-faced Italian sallet, common in the fifteenth century.
Cervelliere -- Steel skull cap, also called an arming cap..
Chanfron -- see shaffron
Chapel de Fer -- Also called a kettle hat. A simple open-faced helmet with a wide brim.
Charnel -- The hinged staple or bolt that secured the fourteenth century helm or great basinet to the breast and backplate.
Chausses -- Mail protection for the legs, either in the form of mail hose or strips of mail laced round the front of the leg.
Close-helmet -- Helmet which, with a full visor and bevor, completely encloses the head and face; modern use of the term tends to refer not to helmets with hinged cheek-pieces opening at the front (the armet) but visored helmets pivoting open on bolts or rivets each side of the skull. Contemporary usage, however, makes no such distinction.
Coat armor -- A quilted garment worn over armor in the fourteenth century. Also called a gambeson, aketon or arming coat.
Coat of fence -- Also called fence, jack, or brigandine. A doublet or tunic lined with small metal plates or, more rarely, just padded with stuffing of tow. See also brigandine and jack.
Coat of plates -- Also called a brigandine, a pair of plates or simply plates. A cloth garment with a number of large plates riveted inside, worn in the fourteenth century.
Cod-piece -- Fabric covering for the groin, latterly padded. Its counter part in armor could be either mail or, more usually, plate.
Coif -- A hood, usually of mail; by the twelfth century it often incorporated a ventail.
Collar -- see gorget
Comb -- The keel-shaped ridge, often very pronounced, that passes from front to back of a helmet over the skull, conferring extra strength and rigidity and contributing to its glancing surfaces. In the mid-sixteenth century, the combs of morion helmets were raised and enlarged to an excessive height for 'fashionable' reasons.
Corslet -- Also spelt corselet. A light half-armor popular in the sixteenth century for general military use (for example, town guards). It consisted of a gorget, breast, back and tassets, full arms and gauntlets; the term can also be applied to the cuirass only.
Couter -- Also spelt cowter. Plate defense for the elbow.
Crinet -- Defense for a horse's neck.
Crupper -- Defense for a horse's rump.
Crest -- A heraldic recognition device fixed to the top of the great helm, introduced in the second half of the thirteenth and in wide use by the fourteenth century.
Cuir Bouli -- also called "cure belly" by the English. A thick leather, boiled in oil or wax, that hardens with a near-steel strength.
Cuirass -- Also called pair of curates. A backplate and breastplate designed to be worn together.
Elbow Cop -- Armor covering the elbow.
Fan Plate -- Projection from an elbow or knee cop designed to prevent a blow from wrapping around and landing in the joint.
Gorget -- Armor protecting the throat. May be a simple collar or a more elaborate design composed of several pieces.
Knee Cop -- Armor covering the knee.
Lames -- Plates of steel, often articulated either by gliding rivets or a concealed strip of leather under the plates, to allow freedom of movement yet still providing protection. Used where a solid sheet of steel would be too constrictive.
Pauldron -- Armor covering the shoulder. Usually large, covering the upper 1/3 of the torso.
Rerebrace -- Armor covering the upper arm from the elbow to the shoulder.
Sabaton -- Armor covering the foot.
Spangenhelm -- method of helm construction using vertical bands for the framework, filled with triangular plates.
Spaulder -- Armor covering the shoulder joint. Not as large as a pauldron.
Tasset -- A plate, usually attached via straps and buckles to the bottom of a breast plate, that provide extra defense for the thighs.
Vambrace -- Armor covering the lower arm from the wrist to the elbow.
Zischagge -- A cavalry helm popular all over Europe in the late 1600's, sometimes called a "lobstertail burgonet". Main features included a domed skullpiece (often fluted), a long adjustable nasal defense, and a neck guard consisting of several lames, or plates.