"Upgradable weapons" refers to weapons that can be enhanced or improved in some way. This can include adding new features, increasing their power, or modifying their abilities to make them stronger or more effective. Full definition
THE LAST RANGER Bring the pain using a collection of upgradable weapons, devastating Nanotrite powers, and Overdrive, the ability to push your guns beyond their mechanical limits. (wccftech.com)
In short, you're not the same fighter you were at the start, much like the Plasmids and upgradable weapons in BioShock drastically change the way you tackle enemies in the back half of the game. (gamesradar.com)
Ride aboard helicopters and tanks aiming to vanquish the entire cartel with the use of powerful upgradable weapons for a total military show down! (teyon.com)