I'm writing a "One big lie" piece where, for the most part, interstellar war doesn't happen due to the cost of FTL travel and the potential destruction caused by a FTL impact on a planet. The only reason anyone would have to do it are "to wipe out ____ because we don't like them," and so the only way for a really interesting conflict to happen is a vaguely plausible political snafu of epic proportions that results in both sides fighting each other with more or less the same goals. Some really strange things have to pile up to get mech suited soldiers on the ground.
More in line with the topic of the thread, the mech suits end up with two divergent design philosophies. One is essentially a lightweight, portable exoskeleton with integrated ballistic armor, probably just spaaace Kevlar, built to be low-maintenance, to use minimal energy just trudging around, and to be fast and agile when needed. The other is a small tank with legs and vaguely arm-like turrets and is controlled via a neural link of some sort to the operator. Their plasma "cannons" are more of a cross between a flamethrower and a nuclear thermal jet engine, for when the thing you want to burn down is made of concrete. Convoys full of engineers, neurosurgeons and fusion reactors follow them everywhere.
The way they're ultimately used, anti-laser defenses wouldn't be necessary, but they would probably have been built into them, considering they use lasers themselves... I doubt silvering would work on something that's meant to walk through walls on a regular basis, so it would probably use thermal conducting ceramics. How shatter-resistant would those likely be? Or is that just something that can't be predicted until it's discovered?
If any of that is too nonsensical, I could probably still change it.