You don't need hose for the edging. That comes from folks choosing convenience over looks. It's just a safety rule to preserve equipment & people on both sides. I use canvas covered rope or rawhide nowadays, but I've seen folks use bare wood that was treated with epoxy, or rounded metal channeling. Even an aspie like me gets that this is about spirit rather than law.
From the West Kingdom Armored Combat Rules:
"Shields shall be edged with leather, padding, or other covering or constructed in such a way as to minimize damage to rattan weapons or other fighters."
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"No bolts, wires, or other objects may project more than 3/8 inch (9mm) from any part of a shield without being padded. Rounded shield bosses are not considered to be projections, handles, or other forms of hand protection are not included in this category."