How to interpret data sheet for an RF 50 Ohm terminator, is it 2 Watt or is it 0.1 Watt
My bet is it's 2 watt. The 100 ohm resistor is listed, but there is probably more than one (or it would be a 100 ohm load) and the resistor is most likely tied to the case. When they are tied to a heatsink, you can run more power through them if the temperature is kept low.
The most important thing would be to follow the temperature rating and keep it below 165C. It's temperature, not power that causes resistors to fail.