...the term "sinister," from heraldry, also has to do with the left - and also has bad connotations in modern language

I seem to recall that way back when, as the Spanish language was evolving from Latin and "dexter" (L. right) became Spanish "derecho," there was sufficient unhappiness with the evil connotations of "sinister" that it was rejected entirely. In seeking a more neutral word for "left" they borrowed from the Basque language up in the Pyrenees mountains, whence the present "izquierda."

Any linguists still participating who can refine my recollection?