Rob,
To handle the 5W HT, you should use a fixed attenuator capable of handling the power. If you also have a step attenuator, they are never rated for more than 1/2W, sometimes less. So to get the %w down to 100mW or so, a 20 dB fixed attenuator will do. If you want to use only the fixed attenuator with the HT, you need to get the power down below 10mW to keep the Tinysa protected, so a 30 dB attenuator will do. I have seen step attenuators on eBay.
Gary
W9TD