Hmm. What do you mean by not worsted? A blazer should be made out of a worsted cloth.
A blazer, if anything, should distinctly not be worsted.
Without some texture (hopsack, fresco, even flannel), it looks like a suitcoat. Blazers also like patch pockets and patch pockets on a worsted cloth always looks wrong (Phat Guido notwithstanding).