Hello, I'm Keith and happy to help you with your question.
The news I impart is, I regret, bad. Whilst there is a disability element available with Working Tax Credit and Child Tax Credit also, you specifically mention pensions in your question so that is probably a non starter. Blind people receive a slightly enhanced Income Tax allowance, but frankly it is peanuts. I see you have already looked at PIPs.
There is a possibility of reduced Council Tax in the event of disability, but that is a matter for your local authority. In some cases there is relief from Road Fund Tax [licencing your motor vehicle]. Also certain disabled products are VAT free. If you receive certain forms of military pensions and the disability was caused by your military service some of these benefits are tax free.
The lack of assistance for disabled people particularly pensioners has been the subject of much recent criticism in the media, but to no avail I regret to say. I am disabled so have an interest. A visit to your local Citizens' Advice Bureau might, and I only say might, bear fruit, but I fear poor pickings.
So sorry to have to rain on your parade.