That sounds so stressful right before a big wedding. You might want to consider the Sigma 85mm f1.4 DG DN Art for Sony E-mount. Its very sharp, but be careful to:

• update the lens firmware right away
• check the eye-af reliability in low light I would suggest doing some test shots first just to be safe. Im always worried about new gear failing me!

Yeah, that 85mm is usually the obvious choice, but unfortunately I had issues with the rendering on my last copy. Total bummer honestly. It just wasnt as good as expected when shooting wide open.

• Sigma 105mm f1.4 DG HSM Art Sony E
• Sigma 50mm f1.4 DG DN Art Sony E The 105mm is technically sharper, tho honestly it felt like a heavy workout by the reception.

To add to the point above: i totally agree that the weight can be a killer during a long wedding day. If you want that prime sharpness but need to stay under budget, i have been super satisfied with these lately.

• Sigma 135mm f1.8 DG HSM Art Sony E
• Sigma 35mm f1.4 DG DN Art Sony E The 135 is basically a sniper rifle and i have been really happy with the results. Its probably the sharpest lens in my bag and the compression for portraits is just gorgeous. Plus it feels like a tank so reliability isnt really an issue... no complaints on build quality at all. That 35mm works well for environmental shots too. You can usually find a used 135 for a steal if you look around. It works well with the Sony AF system so no worries there. Let me know if you need any more info on them, always glad to help out a fellow shooter!

Like someone mentioned, those Sigma lenses are amazing! I love the output! Im always so worried about gear reliability tho, especially for weddings... so stressful! Since you are on a budget, are you looking at buying new or used? Also, do you need something that focuses super fast for the ceremony, or just for the posed portraits? I always worry about focus missing!