Etymology
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shade (n.)

Middle English schade, Kentish ssed, from late Old English scead "partial darkness; shelter, protection," also partly from sceadu "shade, shadow, darkness; shady place, arbor, protection from glare or heat," both from Proto-Germanic *skadwaz (source also of Old Saxon skado, Middle Dutch scade, Dutch schaduw, Old High German scato, German Schatten, Gothic skadus), from PIE *skot-wo-, from root *skoto- "dark, shade." 

shade, shadow, nn. It seems that the difference in form is fairly to be called an accidental one, the first representing the nominative & the second the oblique cases of the same word. The meanings are as closely parallel or intertwined as might be expected from this original identity, the wonder being that, with a differentiation so vague, each form should have maintained its existence by the side of the other. [Fowler]

Figurative use in reference to comparative obscurity is from 1640s. Meaning "a ghost" is from 1610s; dramatic (or mock-dramatic) expression "shades of _____" to invoke or acknowledge a memory is from 1818, from the "ghost" sense. Meaning "lamp cover" is from 1780. Sense of "window blind" first recorded 1845. Meaning "cover to protect the eyes" is from 1801. Meaning "grade of color" first recorded 1680s; that of "degree or gradiation of darkness in a color" is from 1680s (compare nuance, from French nue "cloud"). Meaning "small amount or degree" is from 1782.

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shade (v.)
c. 1400, "to screen from light or heat," from shade (n.). From 1520s as "to cast a shadow over;" figurative use in this sense from 1580s. Sense in painting and drawing is from 1797. In reference to colors, 1819. Related: Shaded; shading.
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lamp-shade (n.)
also lampshade, 1829, from lamp + shade (n.).
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eye-shade (n.)

also eyeshade, "a shade for the eyes," 1808 as a type of headgear, from eye (n.) + shade (n.).

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shades (n.)
"sunglasses," 1958, American English, plural of shade (n.).
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sunshade (n.)
1842, from sun (n.) + shade (n.). Old English had sunsceadu "veil."
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shady (adj.)
"affording shade," 1570s; "protected by shade," 1590s; from shade (n.) + -y (2). Meaning "disreputable" (1862) probably is from earlier university slang sense of "of questionable merit, unreliable" (1848). Related: Shadily; shadiness. Old English had sceadlic "shady, 'shadely.'"
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shed (n.)
"building for storage," 1855, earlier "light, temporary shelter" (late 15c., shadde), possibly a dialectal variant of a specialized use of shade (n.). Originally of the barest sort of shelter. Or from or influenced in sense development by Middle English schudde (shud) "a shed, hut."
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nightshade (n.)

"plant of the genus solanum," with white flowers and black poisonous berries, Middle English night-shade, from Old English nihtscada, literally "shade of night," perhaps in allusion to the berries; see night + shade (n.). A common Germanic compound, cognates: Dutch nachtschade, German Nachtschatten.

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