A verb in The Etymologies of the 1930s glossed “bind” appearing in its Noldorin-style infinitive form gwedi, with an archaic past form gwend/gwenn and a later past gweðant, all under the root ᴹ√WED “bind” (Ety/WED). Given its root, the expected stem form would be ✱gwedh-, so the form gwedi is probably either archaic or malformed.
Neo-Sindarin: For purposes of Neo-Sindarin, I would assume its stem form was gwedh-, and I would modernize its past forms as described in the entry on the Sindarin past tense.
A noun in The Etymologies of the 1930s glossed “bond” derived from ON. weda under the root ᴹ√WED “bind” (Ety/WED). It might be an element of the later word danwedh “ransom” in the name Bar-en-Danwedh “House of Ransom” from The Silmarillion (S/203).