Good day,
I play water polo / swimming 4 times a week, running 2-3 times a week and work out at home 3-4 times a week (various sets of Push-ups, pull-ups & ab crunches).
Overall I'm well built and in good health.

I recently bought a pair of adjustable hand weights that can be a Min of 3kg to a Max of 15kg.
My goal is to increase the muscle mass and volume of my biceps, triceps & shoulders without having to go to the Gym or use steroids & other extras...

What is the best strategy that I should follow:

1.Increase the weight of the hand weights and do less repeats for each set of specialized exercises for the biceps, triceps & shoulders 3 times a week?

Or..

2.Decrease the weight of the hand weights and do more repeats for each set of specialized exercises for the biceps, triceps & shoulders 3 times a week?

Do I have to increase the amount of daily protein / meat that I consume? At the moment I eat red meat 1-2 times a week and the rest of the week, I have a balanced Mediterranean diet, dairy products, carbohydrates, salads, seafood, etc...

I have little experience with weights so any help or other suggestions will be highly appreciated!

Thanks in advance