When you start with Basilisk, there is a time it stops for a while to shoot the drones in the air. There, Panam gives you a sniper rifle ( Uncommon SPT32 GRAD ). It replaced the Overwatch I had in the equipped slot ( which I meticulously upgraded to Legendary status ). When I checked again in the backpack it was not there either. So it was completely disappeared. There is no option to forge an Overwatch without the original so..... damn you Panam!