Don't worry about it. Really. You'll get twenty answers of which ten or so will be from those who have valid sources with PhDs after their names. Frankly no one really knows for sure. Rember this however, Ancient Greeks ran RACES in the stuff, carrying their shields to boot. They fought hours long battles and one man ran what became the Marathon, after running all day before, fighing a battle that lasted several hours that day, and then ran 21 miles to Athens. Wether he wore his armor through all of this is not the point, the point is he had the stamina to do so.
You asked so here it is. Here's my take: the helmet is of bronze or iron and likely ways about the same as a modern helmet (due to the added weight of the crest) thus around 5ibs, the shield likely weighs around 15 to 20ibs, the body armor weight varies widely. After all a solid bronze breast and back will weigh more than a scale or linen cuirass. A solid bronze cuirass I estimate would weigh around 25ibs, while a linen cuirass could come in at 15ibs or so as its actually quite thick and impregnated with glues and boiled in starches (unlike RPGs, I have found cloth armors when properly made to be surprisingly effective). Leather cuirass' are of hardened leather boiled in wax and are surprisingly tough (I've actually tried this, and it's tougher than bronze). It's also quite light and I estimate the weight at around 15ibs.
To give a comparison, a full suit of chain mail of the 12th century variety would weigh in at 60ibs (I know, I've worn the stuff). A medievel shield, made of wood and edged in iron, weighed in at 10 to 15ibs. Greek shields were faced in bronze sheet and made from shaped wooden planks. They were heavy but very strong (and provided the main form of defense) as well as being pretty good sized, a round body stretching from chin to just above the knee. Greek hoplites were in excellent physical condition, and in my games I've not allowed a hoplite character to have a constitution and strength under 13. Historicaly and practicaly anything under this wouldn't hack it.
But as I said, as so long as your warriors have stats at this level, It really isn't a factor, so don't worry about it.