I think that Bulwark should switch places with Fighting Style as the Fighter's Core Ability. The Fighter is supposed to "have mastery of weapons," but the core ability doesn't reflect this. The fighting style options are extremely limited, almost all of them focusing on the type of weapon the character is using rather than how they actually fight. The exception, dual-wielding, is an objectively worse version of the one-handed weapon option, because a character can only dual-wield by holding an individual weapon in each hand. Without the weapon specified by the Fighting Style, the default Fighter lacks any advantage in combat over the other classes. In terms of balance, Fighting Style is a reskinned version of the Wizard's School Mastery, making it noticeably weaker than the core abilities of other classes. The Wizard and Cleric have magic. The Rogue gains not just +1d like the Fighter does but also a versatile Contingency pool that comes up again later in the ability list. Bulwark is a powerful ability that is even recommended outside the context of the Fighter class. It is the ability that currently best represents the Fighter's combat mastery, because it allows the character to outlast the other classes in a conflict. Using this as the Fighter's Core Ability would not just give the Fighter a niche, which it currently lacks, but also rebalance a universally potent multiclass option.