Firearms, my thoughts. First thing that ran through my mind was, "This sure seems to have a Gamma World vibe.

".
Then, if you mean these guns to be a rare OMG Super Weapon! then go for it. On the other hand, if you intend them to be a more standard kind of weapon, maybe a gumshoe noir fantasy or even gunfight at the D&D corral kind of setting, there is a problem, too high of a damage rating, especially for those futuristic weapons. You'd probably want to do something to reduce the damage, or up the PCs HP unless you like party wipes. (This ain't Paranoia, so you probably don't.)
Along those lines, may I suggest that Kevlar undies be made common? (Resistance to Piercing, only from ballistic weapons, aka guns.) As to the lasers, I'd go with Reflec undies. (Resistance to Radiant, only from lasers)
I want guns, but I don't want technology! Well in that case, may I point out that little saying, "Any sufficiently advanced technology is indistinguishable from magic.", and the Doctor Who and Girl Genius variant of, "Any sufficiently advanced magic is indistinguishable from technology.".
In other words, there's reason they aren't manufactured to use the magical properties of the world, as opposed to technological devices employing physics.
Along those lines, gunpowder could be an alchemical creation. Or how about this, the guns don't use gunpowder.
How about the rounds are no longer cartridges filled with powder capped with a bullet. Instead, they are specially crafted crystal rods with runecarved lead caps on one end. Or maybe bone cylinders filled with tiny prayers and runes inscribed on small strips of paper and capped with a bullet.
Along those lines, the energy cell used by the energy weapons could be a charged runeclip, a small package of very thin plates carved with runes and stacked inside a protective case designed to allow the weapons (or other items) to draw out their store of magical power as needed, though it doesn't help spell casters as it's not biocompatible, even for undead. (Maybe there is an undead or other special creature out there that can eat the juice in runeclips. Kind of a rust monster for your ammo.)
If you are worried about a tech item being replaced by a magical analog, don't, it's all engineering. The basic foundation of all engineering is function, and as I'm sure you've heard, form follows function. Many unconnected civilizations have developed very similar solutions to the same problems because of it. Look at bridges. Sure they are made from many materials, but they are all a surface you can travel on to pass over an obstacle. As such, they all have very similar features, despite many different construction materials, construction techniques, and locations.
Here's another idea for you to play with. Want to include some kind of powered armor, but want to make it more "magical". Just explain them as a form of wearable golem.
