Here's some feedback
First, I'm curious as to the primary audience of the website. Is the primary purpose to make for forum members can more easily buy something or make it so that any non-forum person who hears about Martell Knives can buy something. The reason I ask is that its not too non-forum friendly because the first thing you see if things being sold out.
1. Not sure what resolution those first images are (the ones on the main page) but on my ultra wide screen (34inch), they are blurry. I would up the resolution on those to max if possible.
2. I would get rid of the payment type logos (Apple Pay, Discover, JCB, etc). No one cares about payment type until you get to checkout and even then. I mean, is there a payment type you don't take? Amex? If not, the logos just take up space. This isn't a Chinese restaurant.
3. Get rid of powered by Shopify if you can. You're already paying them. No need to advertise for them too.
4. I would segregate products into ready for sale and custom. At the moment, I see that you've transferred all the copy from what you posted in the forum. It's a lot to read for someone new and doesn't clearly articulate what's being offered. For example, can you add the petty configuration options as part of the add to cart/checkout so instead of having to write you what I want, I can just click drop downs and choose?
5. Does Shopify handle international shipping or do you still have to send a separate invoice?
6. I would change tech specs to something else more descriptive like "All about the steel" or "How are the knives made". Combine Tech Specs and Handle Q/A into one section so all that Info is in one place.
7. The copy for standard is somewhat negative. I understand you're trying to explain why those knives are cheaper but from a sales perspective it sounds like you're buying something cheapie. Your knives are not budget knives regardless of materials so standard should be read as baseline, not less than.