The weight of gloves can vary depending on where you slap them on. LOL. When I went to Thailand, it was for my belated honeymoon/1st anniversary, so i did not bring gear, but when i hit Phuket Muay Thai gym for a day to play so to speak, they had left all the gear on the ring apron the night before and it rained. lol.
The gear, Thai Pads, Focus Mitts, Gloves, Shin Guards, Head gear, Belly Pads you name it, were completely rain soaked. I put on a 16oz. pair of gloves after I warmed up, and my god they were heavy as lead, lol. Hitting the heavy bag was like walking through a rain forest, every punch sprayed misty wet glove clouds in the air.
The former champs there training w/ me laughed but were a little offput cause I am sure the Gym owner would give them greif for the equip. mishap later.
When I was working the Thai Pads, the elbows were so damned much easier to throw than my Jab, cross, hook etc.., LOL! Then when I sparred one of the former champs, my arms were very heavy, but the length of my arm compared to the average Thai, he could kick at my thigh and I would leg check and put a Jab on his nose from that far away. LOL. Was very fun, but the gloves can weigh on you alright.
The heavier the gloves the safer the sparring or a fight/match but the bigger gloves make some rely on them too much as shields because of the size. They also get into each others way and can look like the old "PILLOW PUNCHER commercial, lol.
A smaller glove you can not rest on the turtle or peek-a-boo guard as much and a smaller fist can get inside any hole given, and when that smaller gloved fist finds its mark, boom boom, out go the lights.
Just wanted to share, I find that over the years I have gathered several sets of gloves depending on what I prefer to work or what club is doing. I have ripped thru several pairs of the Everlast bag gloves 4306

cause i love to use those for focus mitts, but the larger the glove more likely will be used for sparring, but a hate too heavy of a large fist to spar w/, feel like I got a basketball on each fist. lol.