You should use the “Erase Data” option if someone tries your passcode too many times. As mentioned, even if we did require the AxCrypt password every time, a phone is such a locked down environment that we could not guarantee it to be clean anyway.
The iOS level of protection against passcode attempts is actually pretty solid. The FBI did manage to get around it in an old iPhone 4S after several months and paying an undisclosed (but presumably significant) amount of money to a third party to bypass the protection. More recent versions of iOS does not have that particular vulnerability.