In late writings (see esp. VT/47:37-38), Tolkien reinterpreted this form as a reflexive pronoun (= "self").
Sindarin
im narvi hain echant
I, Narvi, made them
echant
verb. Im Narvi hain ~echant~ 'I Narvi ~made~ them'
im
pronoun. I
im
i
but as subject usually simply the ending -n, as in ónen ”
ni
pronoun. I
nin
i
”me”, genitive nín ”my”, dative anim or enni ”to me, for me”.
v. pa.t. of echad- 'shaped out', shaped and made. Im Narvi hain echant 'I Narvi made them'. edagant was originally a S. pa.t. form which was deleted (together with pa.t. edagad). >> echad-