Wattage on resistors

[Cjhpkns]

So I recently finished wiring up a RGrB Tri-Cree up to my US Apprentice LE v4, and while I was, I had to, of course, hook up resistors to the Red and Royal Blue to make purple. My dad helped me make it, and with his extensive knowledge of electronics and related material, he told me to not use a .47ohm 1/2 watt resistor on my blue LED. He said that the wattage was too low, and told me to get a .47ohm 5 watt resistor. Herein lies my question: could I have used the 1/2 watt resistor? I was using a 4 AAA battery pack (rechargeable, so a bit less than 6 volts). I like my current setup, with the 5 watt resistor, so I'm just asking out of curiosity.