ϯⲗⲁⲥ ˋⲛⲣⲉⲙˋⲛⲬⲏⲙⲓ
ⲗⲁⲥ is masculine so it should be ⲡⲗⲁⲥ or ⲡⲓⲗⲁⲥ
or you can simply say ϯⲙⲉⲧⲣⲉⲙ`ⲛⲭⲏⲙⲓ (The Coptic Language)
or you can say it in the long form ϯⲁⲥⲡⲓ `ⲛⲣⲉⲙ`ⲛⲭⲏⲙⲓ
ϧⲉⲛ ⲡⲓⲉϩⲟⲟⲩ ˋⲛⲤⲁⲃⲃⲁⲧⲟⲛ (ˋⲙⲙⲁϩϣⲁϣϥ)
this is correct but you can make it shorter by just saying `ⲙⲡⲓϣⲁϣϥ
you can also add the word ⲉⲑⲛⲏⲟⲩ if you want to say "next Saturday"
ˋⲡϫⲓⲛⲑⲱⲟⲩϯ ˋⲛⲧⲉ ⲡⲓⲗⲁⲥ ˋⲛⲣⲉⲙˋⲛⲭⲏⲙⲓ `ⲙⲡⲓϣⲁϣϥ (or ϧⲉⲛ ⲡⲓϣⲁϣϥ) ⲉⲑⲛⲏⲟⲩ
ⲡⲁⲓϫⲓⲛⲑⲱⲟⲩϯ ⲫⲁⲓ ⲛⲁ ⲟⲩⲟⲛ ˋⲛⲧⲁϥ ⲡⲓⲟⲩⲏⲃ Ⲡⲓϫⲱⲗ ˋⲛϧⲏⲧϥ
Using ⲟⲩⲟⲛ ˋⲛⲧⲁϥ here is not accurate, and I didn't see it used that way before
You can say any of the following instead
ϧⲉⲛ ⲡⲁⲓϫⲓⲛⲑⲱⲟⲩϯ ⲫⲁⲓ ϥⲛⲁϣⲱⲡⲓ (ϥⲛⲁ`ⲓ) `ⲛϫⲉ ⲡⲓⲟⲩⲏⲃ Ⲡⲓϫⲱⲗ
ⲡⲓⲟⲩⲏⲃ Ⲡⲓϫⲱⲗ ϥⲭⲏ (ϥϣⲟⲡ) ϧⲉⲛ ⲡⲁⲓϫⲓⲛⲑⲱⲟⲩϯ
ⲡⲓⲟⲩⲏⲃ Ⲡⲓϫⲱⲗ ⲛⲁ`ⲓ ⲉⲡⲁⲓϫⲓⲛⲑⲱⲟⲩϯ
Here I used ⲭⲏ, ϣⲟⲡ, ϣⲱⲡⲓ, `ⲓ you can also use ⲣⲁⲟⲩⲱ
ˋⲛⲑⲟϥ ⲡⲉ ˋⲛⲟⲩⲣⲉϥϯⲟⲩⲃⲉ ˋⲛϯⲙⲉⲧⲉⲣⲥⲁϫⲓ ˋⲛⲁⲡⲁⲥ
when you use ⲟⲩ you put ⲡⲉ later for example we say
ⲟⲩⲱⲛϩ ⲉⲃⲟⲗ `ⲙⲡϭⲟⲓⲥ ϫⲉ ⲟⲩⲭⲣⲓⲥⲧⲟⲥ ⲟⲩⲁⲅⲁⲑⲥ ⲡⲉ
also you can't use ⲙⲉⲧ before verb (ⲉⲣⲥⲁϫⲓ is a verb, have u made it up?)
we use ϯϫⲓⲛⲥⲁϫⲓ instead which means (the way words are spoken [pronunciation])
so the correct sentence can be any of the following
ˋⲛⲑⲟϥ ⲟⲩⲣⲉϥϯⲟⲩⲃⲉ ⲡⲉ ˋⲛϯϫⲓⲛⲥⲁϫⲓ ˋⲛⲁⲡⲁⲥ
ˋⲛⲑⲟϥ ⲟⲩⲣⲉϥϯⲟⲩⲃⲉ ˋⲛϯϫⲓⲛⲥⲁϫⲓ ˋⲛⲁⲡⲁⲥ ⲡⲉ
ˋⲛϯⲧⲁϫⲣⲏⲟⲩⲧ ⲁⲛ ⲡⲉ ⲉϩⲣⲏⲓ ⲉϫⲉⲛ
I don't know if it is correct or not (do you?)
but I am sure that ⲛϯⲉⲙⲓ ⲁⲛ ϫⲉ is correct and almost gives the same meaning
ⲡⲱⲥ ϯⲛⲁⲙⲓϣⲓ ϧⲁⲣⲟⲥ ˋⲙⲡⲉϥˋⲙⲑⲟ.
ⲡⲱⲥ is Greek and can be replaced with `ⲛⲁϣ `ⲛⲣⲏϯ if you want
I don't know why you used ϧⲁⲣⲟ= with ⲙⲓϣⲓ, according to the dictionary you should say
ϯⲛⲁⲙⲓϣⲓ ⲉϩⲣⲏⲓ ⲉϫⲟⲥ (I will fight for her)
but for your sentence its better to say
ϯⲛⲁ`ϣⲙⲓϣⲓ ⲉϩⲣⲏⲓ ⲉϫⲟⲥ (I will be able to fight for her)
the complete sentence should be
`ⲛϯⲉⲙⲓ ⲁⲛ ϫⲉ ⲡⲱⲥ (`ⲛⲁϣ `ⲛⲣⲏϯ) ϯⲛⲁ`ϣⲙⲓϣⲓ ⲉϩⲣⲏⲓ ⲉϫⲟⲥ ˋⲙⲡⲉϥˋⲙⲑⲟ (ⲟⲩⲃⲏϥ)
I don't know how I will be able to fight for her in his presence (against him)
ˋϣⲗⲏⲗ ⲉⲑⲃⲏⲧ
In the bible they say ⲧⲱⲃϩ ⲉϫⲉⲛ or ⲧⲱⲃϩ ⲉϩⲣⲏⲓ ⲉϫⲉⲛ
for example
ⲛⲉⲛⲥⲛⲏⲟⲩ ⲧⲱⲃϩ ⲉϩⲣⲏⲓ ⲉϫⲱⲛ our brothers, pray for us. (1 Thessalonians 5:25)
so you should say instead ⲧⲱⲃϩ ⲉϩⲣⲏⲓ ⲉϫⲱⲓ
Ⲡϭⲟⲓⲥ ⲛⲉⲙⲁⲕ