Is that the only thing that the Soul Voice does? I'm also kind of curious how most people play during combat cause I just feel like I'm mashing on things to little effect.
You should be trying to get to the sides or rear. Look at your artes and see which ones specialize on this. Also, there are artes that are mainly buffs, which you should do. Even though I'm not a tank character, if I know my allies are low on health, I will pop a defense arte and then use an arte that grabs the enemy's attention. This helps a lot, but you have to be careful because you might die.
I switch between guns and melee to see which is more effective. Then, I memorize which artes focus on staggering, and which on topple. There is a certain order that you do with your attacks. You want to stagger, topple, then do artes that do more damage during topple state. This process keeps the enemy from attacking and you do more damage. There are artes that heal HP, so make sure you keep an eye out for those.
The battle system is a little bit button mashy, and that was my big problem with the original Xenblade. It felt like I was just standing around and pressing buttons. This game has improved it a lot by giving more weapons, more prompts and special hits. It also lets you attack limbs, which cause damage in different ways. For example, you can sever the tale of those gator-like enemies.