The adjective especial is not just a misheard form of special. It’s a word in its own right, meaning exceptional or of special importance. While special is synonymous with specific or particular, especial is synonymous with uncommon or exceptional. Think of especial in relation to its corresponding adverb, especially. Especially is more common, but especial can apply to qualities that something has especially; for example, an especially sleepy cat has an especial sleepiness.
Special has taken over much of especial‘s territory, though, and is now often used as a synonym of uncommon or exceptional. Because of this, especial may someday fall out of use.
Especial is still relatively strong in British English. Here are a few recent examples from newswriting:
In England, Alexander at first seemed out of his depth when keeping to the spinners, having especial trouble in “reading” Sonny Ramadhin. [Telegraph]
But little dogs are viewed with especial suspicion and derision by Iranian hardliners. [Daily Mail]
[Y]ou can be sure he took especial interest in the first direct meeting for six years of Mike Blair and Chris Cusiter. [Scotsman]