What is best?
I think that is a good question. If you have one sword or spear to re shape a hair dryer might be best. It is going to take some time to get right it never seems to work on the first try and you still have to chill the plastic in room temperature water. You will have to reheat the miniature for each try.This takes a bit of time.
Hot water will remain hot enough for several attempts to reshape the plastic. That is why I prefer hot water.
Hot water has another advantage. Water will never be too hot. It can not get above 212F without turning into steam. This is a bonus for those of you who don't have laser heat gages
the alternate spelling is gauge. The water is less effective with some plastic at about 120 F but with fine cast you will have more time.That is why I say warm water. Depending on code in your county you might be able to use hot tap water if you are quick.
Heat guns are just too hot.
The toaster oven can also be used because obviously you can set the temperature to whatever you want. The oven will evenly heat the plastic so you can bend larger parts. The problem you will have with this is the plastic will cool down fast so you will need to be quick.
I do not recommend the toaster oven for small things like swords or spears.
Hot water is my preference for fine cast.
I needed some bars for a prison for a D&D game. I used hair curlers because they are very cheap. You can not tell from the photo which were heated in the oven or the water. The heat gun damaged the plastic in seconds even with a heat shield.You can see them on the bottom.
I saved the damaged parts for later.
I hope this helps. You will have to experiment with temperature settings I do not know how european gauges are calibrated. Set the temperature gauge on the toaster oven to less than boiling temperature.