I'm always a bit surprised at how many interviewers ask for some kind of work product from your prevoius company.  The work products produced at your previous company belong to that company.  It my opinion, an interviewer asking for samples right up front lack solid interviewing skills.  90% of the time you don't need to see samples to tell if the business analyst will be a good fit. Admittedly, I have asked for samples from candidates, but only on very rare occasions when I had already completed several interviews and there was a specific question left in my mind about  their ability to create a certain type of work product.  If they weren't able to provide it I didn't hold that against them.  It just made my decision a bit more difficult.

With that said, if a company asks for samples and you don't provide any, you may be at a disadvantage, as wrong as that may seem.  You need to determine what makes sense for you.  In the past, I have provided work samples that reflected more generic business processes taking care to not disclose any sensitive information.  When it was necessary I would even black out portion of the samples.  It looked like when the government releases top secret documents.  But remember, even this could be considered inappropriate to some companies, so use your judgement. Companies can take legal action if they so choose, but I've never actually heard of this happening.

For me it's soft skills by a magnitude of 10.  Being a good communicator.  Being abloe to put you in front of clients and being able to trust you can be proactive and manage yourself with minimal guidance.