Old English glæs, from glass (v.). Middle English also had an adjective glazen, from Old English glæsen. The glass snake (1736, actually a limbless lizard) is so called for the fragility of its tail. The glass slipper in "Cinderella" perhaps is an error by Charles Perrault, translating in 1697, mistaking Old French voir "ermine, fur" for verre "glass." In other versions of the tale it is a fur slipper. The proverb about people in glass houses throwing stones is attested by 1779, but earlier forms go back to 17c.:
Who hath glass-windows of his own must take heed how he throws stones at his house. ... He that hath a body made of glass must not throw stones at another. [John Ray, "Handbook of Proverbs," 1670]
Glass-house is from late 14c. as "glass factory," 1838 as "greenhouse."
ware n.
"manufactured goods, goods for sale," Old English waru "article of merchandise," also "protection, guard," hence probably originally "object of care, that which is kept in custody," from Proto-Germanic *waro (source also of Swedish vara, Danish vare, Old Frisian were, Middle Dutch were, Dutch waar, Middle High German, German ware "goods"), from PIE root *wer- (3) "perceive, watch out for."
Usually wares, except in compounds such as hardware, earthenware, etc. Lady ware was a jocular 17c. euphemism for "a woman's private parts" (but sometimes also "male sex organs"), and Middle English had ape-ware "deceptive or false ware; tricks" (mid-13c.).