Say you'd get 4% melee on each part you'd hit 32% melee. 30% isn't that bad actually althrough you could get a little more if you'd spend the time/money, 19% weapon attack is a bit meh tho.
You can get more melee on endgame weapons by making them legendary and getting a Lucky roll on Ferk wep, 2k insig's a roll.
Anyway I don't see why you'd roll a melee weapon on a giant while they have such insane crit. dmg but well we're talking about TheBase here lmao.