I think powered armour is a waste of a good lifting suit, and a sword would be a waste of a good design. We already have Smgs for killing folk in close quarters, but they've even longer reach than a sword. Sword adds nothing do the equation.
Here, if your insistant on adding some armour and melee let's do it right. Make it a part of something greater.
Combat Engineering Kit
The combat engineering kit is, essentially a way to make our Mountain Men a viable force multiplier on the front lines and take full advantage of it's capabilities. Consisting of a giant tower shield, or more correctly, pavise of steel, design to be braced against a shoulder and held with one hand allowing the Lifting Suit to march undaunted in combat, completely protected from the front. I'm thinking a slight bend to the shield to influence deflection up or to the sides rather than penetration, with downward slope that deflects up we'd need additional metal stands down the side, that we might link multipule pavises side by side or at 90 degrees to create an instant barrier that could be left for our standard infantry.
By not trying to cover every bit of our suits and not caring about the mobility of our armour, since it's not designed to move, we can make a thicker an better shield against bullets able to stand up to our own machine guns, without any need for weaker moving parts. Sure it's only pointed forwards, but then that just means all the armour is at the front rather'n be spread out.
Now, note how I said, Combat Engineering 'Kit'? The whole point of this would be to allow our men to advance and entrench in a combat situation, to this end I suggest we enhance our classic entrenching tool to stand up to the rigours of use our new lifting suits can supply. Too many have broken due to the increase demands a greater strength requires. To this end I believe an enlarged entrenching tool built of this new lighter than steel alloy would serve admirably, perhaps with sharpened sides, that they might be used like battle axes in one hand or two, should the occasion require it.
Now, even improving upon the classic shovel is not quite fast enough, so I suggest we supply our Combat Engineers with a dozen explosive charges attached to stakes, that they might be hammered down and blast open the ground in order to rapidly entrench. Add in the detonator, then of course to round it out I'd suggest a supply of empty burlap sacks, for the filling with soil and fortifying the new entrenchments.
So, to summerize, I suggest a giant barricade of metal able to be moved only due to the strength of our suits but also able to stand freely, A lighter than steel entrenching tool that can double as a battleaxe, a dozen explosives meant to be hammered into the ground to blow starting entrenchments, a detonator for said explosives, and a dozen large sacks or so to turn into big sandbags.
~Yami, Mad Genius Scientist.