Looking for new paddle and wondering what the view on the blades getting narrower/smaller. Fanatic offer 7.25 and a 6.75. but fail to explain why sizing. Naish & starboard are around 7.25/7.50.

Is it down to shoulder strength choice, or fast paddling for waves. My boards are Vbox 7.6, 27 and a TC/blane 8.8ft 29". Currently using a 7.5 but its adjustable and not liking the feel of the shaft, blance etc, so hard to tell if blade size is working for me or not.

It's a hugely personal choice. Most people these days are using blades within the 80-90sq inches for surfing. But there are advantages of bigger blades if you have the power to use them. Yes, it's mostly about acceleration for wave catching, but there are several other factors too (eg. bracing), and some people prefer using fewer and harder strokes to catch a wave rather than paddling like the Energizer bunny.

You'll only really know what is right for you by trying a variety of different paddles.