I've had a goal for over a year now to drop 30 pounds between me and my kit. So far I've lost about 12 pounds from my lazy gut, and cut the weight of my body harness and leg harness in half.
I switched the body harness from a Churburg #13 (the segmented one) in 16 gague stainless to 0.032" thick 4130 version of the Churburg #14. The #14 is just 3 pieces, so there are fewer rivets, no brass work and less leather. It was a lot harder to do. With the thinner metal and the warping during the quench the whole thing really needs more work. I got a compliment on it just last night, but the surface has ripples that drive me nuts, the back plates don't sit flush, and it's not completely symetrical.
I kept basically the same design of leg harness I've been using for years. It's my own pattern based more loosely than I'd like on a number of late 14th and early 15th century examples. I had an issue with covering the inside of the knee on the last itteration, so I had to rivet on little fans to them. I adjusted the pattern this time to cover that. Otherwise just making it in 0.032" 4130 instead of 16ga stainless cut the weight in half.
I've been playing with arm harness designs for a bit based on the Chartres arm harness seen here. It doesn' t seem to have lames, and the hinge is integral, so it's pretty light weight. The best articulation I've gotten from this style is OK, but a bit stiff. I've had some trouble with the upper part of the vambrace digging into my forearm. It fits fine when I first put it on, but after fighting for a bit, my arm swells with blood and it pinches. So there's some modification to do. I'm still not sure if I want to continue down that road or go with one of the Churburg designs, which have lames.
The other thing I really want to replace are my greaves. Back in 1993 Greggor (my knight) pointed me to a pair of old leather greaves which were litterally collecting mold in his basement. I cleaned them off, and have worn them ever since. They're the only things I have from my original fighting kit, and they've worked extrodinarily well. Some of the straps are even still originals. I should be able to cut down on weight and bulk by replacing them with steel. Since my shins rarely get hit I've been kicking around the idea of doing them in 0.025" 4130. Working in something so thin doesn't leave a lot of margin for error, and the shaping around the ankle is tricky.
Further down my list of things to replace are my gauntlets and my helm. I like having some mass to protect my head, though mine right now is 17.5 lbs. It's also a closed face design, and it's more challenging to fight in. It's very difficult to be heard, so commanding in a melee is really tough. I started pounding out a great bascinet like in King Renee's tournament book. http://www.princeton.edu/~ezb/rene/crests.gif My pattern needs a lot of work, and I need much more practice raising such a big piece. I wore a hole right through the top, and have to start over when the pain of loosing all that time and effort fades. I still like the design, since it can be lighter than what I have, doesn't need an avantail, fits a bit better with some of the slightly later period stuff I'm now capable of making, and has better vision and air flow than what I'm wearing now.
After all of this, sabattons would be nice. Meanwhile, I have the open shop nights to run. I don't get much done on my own kit during those nights, but they really help to motivate me. A lot of armouring can be a solitary activity, and without anyone to share your work with and bounce ideas off it's not as much fun.