https://www.grimtools.com/calc/JVlGnob2
I am trying to build a sword of “gun and shield bombsquad” type of character. It’s super fun already! However, I often get stuck, especially when the enemy can heal themselves or has high fire resistance, just sort of wailing at them for ages before either of us have health bars move.
Without ruining the spirit of the build, is there a way to improve it? The damage problem is obviously a main focus, but ANY advice helps!
First, you have a lot of different abilities with a low number of points and all different damage types. At your level you should pick 1-2 and then support them with other passives, rather than a lot of small abilities that take longer to kill an enemy. I try to have as many active abilities as I have devotion effects to bind them to, and I pump the maximum amount of points into the node that has the damage type I want (not always the base ability).
Fire is the natural damage type for Shieldbreaker leveling up, so let’s say you decide to pump 12 points into Blackwater Cocktail and bind it to Fiend. Skip the Demon Fire node, since you don’t care about Chaos, and go straight to Agonizing Flames to get more fire damage and a resistance shred. But you will run into enemies that have even more fire resistance. There are a lot of fire-resistant enemies, and the abilities you get that shred Fire resistance are only available fairly late, but you can get some early on through devotions - Solael’s Witchblade and Viper are good for you. That will help you out against enemies that have higher fire resist. Then you maybe bind Solael’s Witchblade to Thermite Mine which is another resist shred. Suddenly those fire-resistant enemies just fall over like they have no resistance.
As you get more points available then you can add more abilities, but don’t neglect Flame Touched and Vindictive Flame - both of those are mega overweight for a Shieldbreaker.
Hi, it’s alot easier at low lvl to focus on 1 source of damage. In your case: fire (and some burn, the dot effect)
As you are low lvl i would also suggest to not take so many skills.
For now i would lose points in: fire strike line, flashbang line, grenado line, mortar line. Also remove the points from temper and ulzuin wrath and concussive bomb.
Those points i would put in:
12/12 blackwater cocktail
12/12 flame touch
rest in canister bomb
I see you use a component in your chest. You really should use more components as you find them. Main focus on resists. Same for gearing really.
2 components you need to add asap are: entchanted flint in your shield and flintcore bolts in your gun. These will give a passive aura which will give nice dmg boost and also a great spammable skill: greater fireblast.
Idea is to use BWC and CB on cd as you run around/kite and spam greater fireblast when they are on cd.
End game:
As you lvl you want more points in blast shield (8 ish) / thermite mine (8 ish) / ulzuin chosen (max) / agonzing flames / improve casing. (demo part) and aim for 1 point in guardian and 12/12 celestial presence and 12/12 divine mandate. Also ascension i like at 12/12 and at least 1-4 points in clarity of purpose. temper/heaven are ok but dont put to many points in them.
For exemple: https://www.grimtools.com/calc/r2BzaJW2
gl 
Lvl 33 is no build. It’s just whatever happened to drop. You need to focus on one skill one filler plus debuffs (resistance reduction mostly) as you level. Those 1p/2p mains make no sense in GD.
https://www.grimtools.com/calc/4Vxkx3a2 I used more or less the same amount of points. Note the component on the weapon. It’s for Greater Fireblast. You use that and BwC and Mines. Fireblast will deal more dmg for free than all the points you put in Firestrike at this point. Plus you got 25 (Agonizing) + 34 (Mines) = 59 resistance reduction now, so no more nigh immortal Burning Dead lol. Also, I took you Bat for Fiend as it will give you an ok heals, and Sailor for Candle for run speed so that it doesn’t drag.
Keep pumping points in Oathkeeper and get to Guardians asap. Until you get enough points to fill Firestrike line like max-12/max-1-max, and get some more attack speed, it just doesn’t pay to use it at all. In devotions, get Spider, Hawk, Magi next and go in the general direction of Torch. Or stray a little and pick up Phoenix (would be better with an off-hand than a shield, though, everything is better with an off-hand except retaliation especially the bomberman style as off-hands reduce cooldown on those bombs).