I misread a post on customers_suck just now which referred to the place where someone worked, a welding safety products company. I initially read it as wedding safety products company and now I'm trying to decide what such a company would produce.
Hi-vis fluorescent jackets for the bride and groom, to aid in identification and to make sure everyone could see them.
A lifeline for the best man, to which he or she could clip the wedding rings, to avoid those last minute loss situations.
Anti-slip matting for the aisle, protecting those walking down it from embarrassing falls.
Hearing protection for those times when the celebrant simply won't stop waffling.
Hard hats might, I suppose, be a little excessive; confetti, flower petals, rice, bird seed, whatever - it's not usually that heavy. Although eye protection for the happy couple might be useful; some of that stuff is sharp...
Appropriate signage would be a must. "Warning - Dazzling Smiles", "Beware Drunken Relatives", "Danger Of Confetti Next Three Miles"