It seems that you could use Fair, Fade or Faint (there might be others)
Fair
and its other forms
fair (adj.) Also (early) faȝer, faier, fei(e)r, vair, fare, fer(e,
war, fæger, fægerra, fægrost
According to the Middle English dictionary from Umich
(a) Light, bright, or shining (as opposed to dark); (b) of persons:
light of complexion or color of hair and eyes; fair.
It seems to have been used with color (other than applied to skin or complexion):
Found at least one reference as cited in Altenglische legenden ...
Horstmann, Carl, ed. b. 1851.
þat þis on schal beo fair blu cloth
...
Faint
Of things, actions, functions, etc.: weak, feeble; impaired, poor;
pale (color)...
...
Fade
Of color or things having color: lacking in brilliance; pale,
discolored, dim; dull; fade-heued.
(Fade-heued meaning "light-colored")
>c1300 SLeg.Mich.(LdMisc 108) 672: Ho-so hath of þe eorþe mest, he is..Of fade [vr. vad] colur.
...
As for your example of "whyte Russet" I think russet is used here in the sense of
"a serviceable woolen cloth, usu. of plain or subdued color & usu.
worn by the poor or by workingmen (also by the Duke of Suffolk as a
sea-cloak)"
the same way Whites can be used for "clothes usually of white color" in modern sense, Russet is used by analogy for the piece of cloth usually of the color Russet or the fabric material itself with which one makes russets.
See here in The Stonor letters and papers, 1290-1483; ed. for the Royal historical society, from the original documents in the Public record office, by Charles Lethbridge Kingsford, for Russet used with the color Black, for example, in the sense of piece of cloth or fabric material.
a ȝerde off blake russet karyssey to make Richert Baron a dublet
a payre off hosyn off russet karyssey,
Item a gowne of russet furryd wt blakke,
another example of russet used in the sense of fabric.
And is as gladde of a goune · of a graye russet /
So the answer is I don't think whyte russet mean a light russet (color).
Best Answer
To answer your first question: blue is not an object in this sentence. It is a complement, more precisely a predicative complement. There are two sorts of predicative complements: subject-related predicative complement (also known as a subject complement) and object-related predicative complement (a.k.a. object complement).
Blue in your sentence is a subject complement. A subject complement follows a linking verb and gives more information about the subject by identifying or describing it. It can be a noun, pronoun or an adjective (or a noun phrase, or an adjective phrase...). When it is a noun or a pronoun (or a noun phrase) we talk about a predicate nominative. When it is an adjective we talk about a predicate adjective. This is what "blue" in the example is.
How do you know if something is a subject complement or an object in a sentence?
Only transitive verbs can have direct objects. So, check the dictionary definitions of the verb in your sentence (most dictionaries will state if the verb is transitive, intransitive or can be both).
Try to make a passive voice construction. The object becomes the subject in the passive. A (predicative) complement cannot become the subject of a passive clause.
An adjective cannot function as an object. Ever.
** We could dig deeper into this but I think we shouldn't because: a) it might confuse you and b) it might confuse me. So we'll leave it at that.
To answer your second question: It is a clause and a sentence. As Kathy said (and according to Longman English Grammar) a clause is
A sentence can contain one or more clauses. If it contains one clause ("The sky is blue") it is a simple sentence. If it contains more clauses it can be a compound sentence or a complex sentence.