Words such as weird, and many others, make fools of those who think there are rigid rules to the English language - a language made up of so many borrowed words that spelling was, until quite recently, optional.
We'd have trouble reading Chaucer or Shakespeare in their original manuscripts; like other literate English people they considered the spelling of even their own names less important than the ideas they were attempting to convey. Not a bad outlook, really.
Good spelling matters today, and its effect upon people is important; they form opinions of others from spelling and grammar, and general literacy.
When in doubt, consult a dictionary. OneLook is good because it trawls many other dictionaries and also uses fuzzy searching where necessary.
God is good. :]