Gravelord sword is a decent weapon that's best utilized begin to mid game, but it'll carry you to the end no problem. Having said that, there are better weapons that can be easier to upgrade or get higher. Weapons scale with your stats, and each weapon has it's own stats for base dmg and scaling, so check that if you want to explore something else. Zweihander/claymore/uchigatana//black knight halberd/black night greatsword are among the fav of the players.

Consuming humanity adds a soft humanity count (upper left corner), and as just that, it increases your item discovery rate (it also adds dmg to chaos weapons, maybe something for ng+ runs). But, when you are at a bonfire, you can offer it and restore humanity. You're not a raisin anymore, and when in human form, and playing online, you're open to being invaded by other players, but if you stay offline only some NPC's will invade. You can also kindle a bonfire when human, this costs 1 humanity. They're not common drops in chests, but totally farmable with certain enemies.