The Imperium is not a technologically orientated society, but it is very much a technologically advanced one. The Mechanicus have a great understanding of science and technology, even if cloaked in mysticism. The Mechanicus investigation detailed in the Necron Codex, for example, demonstrates a great deal of understanding of the processes of empiricism, experimentation, and understanding of scientific laws (which the Necron weapons appear to violate in so many ways, understandible considering how insanely advanced their tech is [FTL in real space]).
The Imperium can produce highly effective man portable laser weapons, which is an incredible accomplishment. That these weapons are so logistically robust that you can recharge their power cells by throwing them into a fire even more so. They have highly effective forcefield technology, super materials used not only as armour, but to build multikilometer tall buildings and hive spires. Antigravity. FTL. Extraordinarily potent power generation systems that can power enormously powerful energy weapons and accelerate multiple kilometer long space ships at tens or hundreds of gravities. Ships tough enough to survive that kind of acceleration. Nanotechnology and computer systems built into tattoos.
Don't be fueled by the more mystical terminology, the rejection of Artificial Intelligence, or the ignorance of the common man. The technology of the Imperium of Man is frighteningly advanced and capable.