Yes, you can still use a clothing bless deed on the Kasa. Just did it about a month ago.
That brings me to another question. I bought a Hat of the Magi the other day that didn't say blessed on it, but when I tried to use a clothing bless deed on it, it said it was already blessed. I did go out and get myself killed and it did stay in the pack, but I could have sworn that I've seen Hat of the Magi's that had the bless tag showing. Am I missing something?