Brawler Ward shield, melee or Dragon relic, Breaker COM and some guns with good melee bonus and you’re set. Of course anointed bonus for melee will help a lot.
Krieg main here, it seems we facing the same problem has bl2 before they introduced dlc characters, except in bl3 they said they wont. only way to make a viable samara melee build is to use a very specific build with artifacts, shields, weapons and annointed that increase her melee
https://bl3skills.com/siren/#5050353102001100000000000005005150013200
Thats the build i am using for slaughtershaft on mayhem 3 tvhm.
For gear u would need a brawler ward (Graveward drop), Buttplug, Facepunsher and then what ever you like, usually i run with a good corrosive weapon and brainstormer. Also the Unleash the Dragon (El Dragon Jr.) artifact is kinda mandatory. I run with Fist over Matter with Glamour to get the Samsora stacks, Allure would also be ok since Glamour is bugged right now but i still prefer Glamour.
Mindfulness is personal preferance, it makes your shield recharge faster so you lose your melee bonus quicker but the mobility it provides is really nice.
Brawl is not just about melee. Any Maliwan Shotgun dose amazing things with this tree.
If your looking for an edge I have one little secret most people seem to over look and that is Cryo and Radiation.
Frozen enemies take hellalot of melee damage. The Frozen heart shield is my BFF for this. It also makes anything close to me unable to attack me
As for Radiation I suggests a Maliwan Shockwave mixed with Personal Space maxed out. This is not always 100% viable with some mayhem modifiers screwing the combo but when it is good it is damn good.
I think of melee like a Glory Kill in DOOM I weaken the enemy with my guns then move in for a decisive finish.