Blend
Middle English: probably of Scandinavian origin and related to Old Norse blanda ‘to mix’.
wiktionary
From Middle English blenden, either from Old English blandan, blondan, ġeblandan, ġeblendan [1] or from Old Norse blanda(“to blend, mix”) [2] (which was originally a strong verb with the present-tense stem blend [3]; compare blendingr(“a blending, a mixture; a half-breed”) [4]), whence also Danish blande, or from a blend of the Old English and Old Norse terms; both ultimately from Proto-Germanic *blandaną(“to blend; mix; combine”). [5] Compare Middle Dutch blanden(“to mix”), Gothic 𐌱𐌻𐌰𐌽𐌳𐌰𐌽( blandan), Old Church Slavonic блєсти(blesti, “to go astray”).
etymonline
blend (v.)
c. 1300, blenden, "to mix in such a way as to become inextinguishable, mingle, stir up a liquid," in northern writers, from or akin to rare Old English blandan "to mix" (Mercian blondan) or Old Norse blanda "to mix," or a combination of the two; from Proto-Germanic *blandan "to mix," which comes via a notion of "to make cloudy" from an extended Germanic form of the PIE root *bhel- (1) "to shine, flash, burn."
Compare Old Saxon and Old High German blantan, Gothic blandan, Middle High German blenden "to mix;" German Blendling "bastard, mongrel," and, outside Germanic, Lithuanian blandus "troubled, turbid, thick;" Old Church Slavonic blesti "to go astray." Figurative sense of "mingle closely" is from early 14c. Related: Blended; blending.
blend (n.)
"mixture formed by blending," 1860, from blend (v.).
