> "Komið!", "Farið!", Come!, Go!. Here -ið refers to "þið" you plural.

Hi Uoden,

I guess you know all this, but just to elabourate: Modern
Icelandic 'þið' "you" pl. was earlier 'þit' "you (two)", earlier
still 'it' (cf. Old English 'git'). The 2nd person plural verb
ending -ið goes back to Proto-Germanic -iþ or -id. The pronoun 'þit'
acquired its 'þ' from this verb ending due to confusion over where one
word ended and the next began.

komiþ it > komiþit > komi þit / komiþ þit (=komið þit).

Likewise the old 2nd person plural:

komiþ ér > komiþér > komi þér / komiþ þér (=komið þér).

Some English examples of this sort of thing: an eke-name ('eke' =
Icelandic 'auk') > a nickname; a norange > an orange (cf.
Arabic 'naaranj', Persian 'naarang').

I don't know how old the change of unstressed final 't' to 'ð' is, but
I think it must go back at least to the 13th century, even though the
standardized/normalized Old Norse spelling used in modern textbooks
uses forms like 'þit', 'kallat' for MnIc. 'þið', 'kallað'.

Lama Nom