I recently was playing around with a Caestus run and I had a thought: Is Raw Caestus one of the greatest back-up weapon for early casters (ie – spell-based)? While this is mostly PVE-centric, I've had some luck with Caestus in PVP as well (particularly when you catch invaders off-guard). As I see it, here are the main benefits of Raw Caestus for casters:
No wasted physical stats. For Sorcerors, there's no investment needed to use the Caestus right out of the gate. Sure, some DEX investment is always a good idea for little bumps to cast speed, but you save a bunch of points on Vitality (since it's extremely light), Stamina (since it uses very little stamina), and Strength.
Punches in bunches. As noted above, even when dual-striking, the Caestus uses very little stamina, allowing you to just spit out hits left and right (literally). The damage and range of the Caestus isn't great…but when you combine it with a resin or buff? You're getting almost 75% more damage per hit (depending on the buff and any gear to boost damage type). I've found this adds up tremendously when using the dual-wield L1 attack. The +3 Raw Caestus (using spare titanite shards) with Great Magic Weapon, Heretic Staff, and Dusk Crown (all of which are attainable after only beating a single boss) yields a damage output of 283 AR PER HIT. It's not a true combo, so you have to be careful about spamming, but if the person you're punching doesn't have poise and/or a fast enough attack to get out of it, you can burn them down extremely fast.
Perseverance. The weapon art for Caestus has been a terrific tool. If an enemy gets past your spells, you can use it to reduce damage taken in melee (which is super cool for glass cannon types) while you either trade or try to GTFO. I can't tell you how many times I've beat invaders to death because they don't anticipate a mage standing his ground and just letting fly with the flurries mentioned above. Unless they're smart about it, they're dead before they understand what's happening. Unfortunately, the skill doesn't appear to affect spell casting, meaning you can't use it to buff yourself for those big Magic Greatsword swings. But, still, having that extra damage reduction without the weight of a shield is pretty nice.
Obviously, this is probably not going to scale to the end-game content but, hopefully, your spells will be strong enough with enough variety that you won't need to worry about melee. Maybe I'm crazy and overvaluing it's usefulness in the early game, but in my opinion, it feels like I've found an indispensable tool for early casting runs.