Sappers were issued with sidearms in addition to their primary weapon. I was issued an Uzi SMG and a Browning Hi-power. The fact I issued with a sidearm that meant I was armed in situations where carrying my Uzi wasn't practical, like at HQ, in town or while doing "welfare checks" on the "lay sisters" at the mission.
Carrying a sidearm around all the time was sometimes a pain but you got used to it. I can say that carrying it all the time did make it much more familiar and easier to use. I felt naked when I got discharged, it was the first time in years I wasn't carrying a pistol!
To be fair my sidearm as an adjunct to my primary weapon wasn't very effective. I only once had to use my Browning when I was also armed with my primary weapon. All the other times I used a pistol it was the only weapon I had.