In The Hand of Fear, the Doctor implies that the TARDIS' state of temporal grace is linked directly to its dimensional transcendence ('In a sense, you see, we don't exist while we're in here'), and therefore that any weapon will not work in the TARDIS. (Taken to its logical conclusion, the Doctor would seem to be indicating that people inside the TARDIS do not need food, water, warmth, etc. because they 'don't exist'!) However, we only see that Eldrad's mental powers do not function.
In The Invasion of Time patrol stasers do not work within the TARDIS (which would seem to be a reasonable safe guard for Time Lords to build into their weapons), but other weapons do function in the TARDIS, including those of K-9 and the Sontarans. (See also The Visitation (Nyssa's sonic device), Earthshock and Attack of the Cybermen.)
It seems that the Doctor often talks of 'temporal grace' in an attempt to minimise disruption within the TARDIS, but plainly this 'feature' does not exist. Even Nyssa comes to believe that weapons shouldn't work in the TARDIS, but when in Arc of Infinity she asks the Doctor about the state of temporal grace not stopping the Cybermen's guns in Earthshock, he simply replies 'Nobody's perfect.'