I believe Defende
I have never run across Assiste
. Where did you get that?
I would use Adiuve
rather than Adivve
Someone told you that in Classical Latin V
was used for both U
That's true, but in Classical Latin, there were no lower-case letters either.
In the Latin that is used for mottoes and such you will see a mixture of
upper- and lower-case letters and the use of the letter u