https://www.kanjipedia.jp/kotoba/0005845100
Most kokugos describe laces / threads / leather straps ("革や糸を緋色に染めたもの。"). Most of the definitions also end with a "また、その鎧。" note, so maybe we should have two senses.

Google N-gram Corpus Counts
╭─ーーーー─┬───────┬───────╮
│ 緋縅　　 │ 1,879 │ 52.2% │ - add (most kokugos)
│ 緋威　　 │   712 │ 19.8% │ - add (iwakoku, smk, grk)
│ 火威　　 │   490 │ 13.6% │ - add (daijs, smk, grk)
│ 緋おどし │    94 │  2.6% │ - add, sK
│ 火縅　　 │     0 │  0.0% │ - add, sK (mentioned in daijirin)
│ 緋縅し　 │     0 │  0.0% │ - sK (only meikyo)
│ 氷魚縅　 │     0 │  0.0% │
│ 氷魚威　 │     0 │  0.0% │
│ ひおどし │   423 │ 11.8% │
╰─ーーーー─┴───────┴───────╯

@@ -4,0 +5,17 @@
+<keb>緋縅</keb>
+</k_ele>
+<k_ele>
+<keb>緋威</keb>
+</k_ele>
+<k_ele>
+<keb>火威</keb>
+</k_ele>
+<k_ele>
+<keb>緋おどし</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>火縅</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
+<k_ele>
@@ -5,0 +23 @@
+<ke_inf>&sK;</ke_inf>
@@ -12 +30,7 @@
-<gloss>scarlet-threaded suit of armor (armour)</gloss>
+<misc>&hist;</misc>
+<gloss>scarlet bindings used with a traditional Japanese suit of armor</gloss>
+</sense>
+<sense>
+<pos>&n;</pos>
+<misc>&hist;</misc>
+<gloss>scarlet-threaded suit of armor</gloss>