Question about Clan Fraser Crest

[Tobus]

I was taught that the "ê" was used to show that a letter had been deleted at some time in the past, and that letter was often a vowel or the letter "s"
an example would be fête instead of feste
just a memory from my childhood french!

Now we may be getting somewhere! Perhaps the Fraser clan motto is an archaic form of French, which would make perfect sense. It would be correct for the way French was written then, but outdated in today's French.

Can someone else verify this? That would almost be too perfect of an explanation!

*edited to add:

I do take particular interest in this, because the Fraser of Lovat clan crest is very similar to Colquhoun. They both have the stag's head. Fraser says "Je suis prest" while Colquhoun says "Si je puis". It's very easy to confuse one for the other at first glance!