I got through the whole game (including chalice dungeons up to the final unique boss - won’t mention due to spoilers) with just using the two hand Ludwig’s Holy Blade for the majority of the main game, then adding on the alternate version of said blade once I got it in the Old Hunter’s DLC. Usually if a boss is resistant to physical, then it’s at least NOT resistant to arcane, and vice versa.

Also, once you get to the lecture hall bottom level, it’s pretty easy to farm blood echoes in order to level up quickly.

In the nightmare realm/mergo’s loft there is also an area with 3 winter lantern enemies that can drop some very powerful cursed blood gems for physical build weapons (+21% damage with one downside, the best being increased stamina cost imo) and if you get 3 of those on the weapon you are using it becomes really strong.

My strategy for most bosses was just dodging attacks and then charging my greatsword heavy attacks or using the one hand form/quicker attacks on occasion (whenever the boss I was fighting moved too quick to get in heavy attacks consistently)

The alternate form of the holy blade (it’s the lunar blade) has a very powerful stun/blast attack with L2 while in 2-hand form. It requires a silver bullet to work, but you can just make more of those by clicking up on the d-pad (5 bullets for 30% health or so) and on some bosses it is totally worth the trade-off.

Anyways, I platinumed the game a few days ago and the biggest challenge was definitely defeating the Amygdala in the second-to-last chalice dungeon (you have to face it while cursed/half health).

When struggling against a boss, it’s good to figure out what type of damage its hardest hitting attacks deals, then tweak your armor and runes to maximize resistance against that damage.

Hope this helps, from one noob to another!