Is that 26 pounds the weight of just the shell or does that include the other stuff that's needed to make the suit viable? For example, one problem is removing body heat. NASA uses water to absorb the heat for removal. The shell would need thermal systems to control the astronaut's body temperature and radiation shielding to be useful on Mars. If you look at the Apollo moon suits, you'll find that most of the weight was in the backpack. It contained the consumables (oxygen and water) necessary for long EVAs as well as electrical, telemetry, and communications subsystems. Modern technology can provide lighter batteries and radios but there may not be much they can do to cut oxygen consumption very much over Apollo. The suits will have to be a lot lighter than those used on the moon if for no other reason then the fact that gravity on Mars is twice that of the moon.