We know how big the various incarnations of Godzilla are (165' tall to 1000' tall depending on the version), but how big is Tiamat? In 5e there is no description other than her size Gargantuan. However, in 5e that just stands for anything bigger than Huge. however, the Tarrasque does provide a size in 5e: "...is fifty feet tall and seventy feet long,..." So, even the smallest version of Godzilla is 3x the size of the Tarrasque.
So what does this mean for people with point sticks. Well, the Big G is supposed to have very tough hide. So starting with a RL animal with tough skin, the whale shark, we get an estimate of the smallest G with a skin thickness in the 3' range and the largest with a skin thickness in the 16' range. So, your pointy stick fighter (or any other character really) is going to have a hard time getting that point stick to do much of anything.
Conversely, a 165' giant constructed like a scaled up human would only have skin 4" thick or so.