One of the more versatile rewards from the original Dark Souls is the Soul of Sif. This item can be turned into three different distinct rewards -- the Greatsword of Artorias, the Greatshield of Atorias and a pretty hefty amount of souls -- each with its own benefits that make them worth obtaining. It's possible to get all three with repeat playthroughs, with one of the possible weapons even having a secondary variant.
The ways players can convert the boss soul they get from one of Dark Souls' many bosses into both the Greatsword and the Greatshield involve bringing a certain amount of items to the Giant Blacksmith at Anor Londo. The Greatsword, the Cursed greatsword and the Shield each require a different kind of item to be delivered to the Giant Blacksmith. Here's a quick rundown on each of the possible items players can use the Soul of Sif for and how players can make each time.
Greatsword of Artorias
Players can ascend either a +10 Broken Sword or a +10 Greatsword/Straight Sword into the Greatsword of Artorias or the cursed Greatsword of Artorias, respectively. The primary difference comes down to the kinds of damage these two swords do, though there are other minor changes worth mentioning. Looking at the fully upgraded versions of each weapon, the cursed version of the Greatsword does 267 physical damage while the normal Greatsword does 180 physical damage and 127 magic damage. The cursed Greatsword is also capable of killing ghosts.
This means that the non-cursed variant does more damage overall, with said damage split between two different types. The downside is that if an enemy resists physical or magical damage, the non-cursed sword will actually do around half the amount of damage as the cursed variant. This might make the cursed version seem like the better pick, though some smaller differences are worth noting.
The non-cursed Greatsword has less durability and stability than the cursed version, meaning it's a bit less reliable and will cost more stamina to block while using the blade. Generally, the cursed version of the blade sacrifices damage for reliability, making it a good option depending on the player's build. The non-cursed Greatsword, meanwhile, is a bit more of a glass cannon.
Greatshield of Artorias
Another option is to ascend the Soul of Sif into the Greatshield of Artorias, which requires a +10 Shield Weapon to be given to the Giant Blacksmith. This shield has a pretty hefty amount of reasons to create it, making it a strong candidate to be one of the best shields in the game. The shield has the highest stability out of any shield in the game that isn't crystal. The Greatshield of Artorias has a stability stat of 600.
The Greatshield also has a few unique traits that make it worth creating. For one, it can block any status effects that may otherwise go through other shields, though this ability doesn't apply to area of effect attacks or ambient effects. Oddly enough, there's a chance for the shield's ability to not work in multiplayer, failing to block bleed, poison or toxic status effects.
What if You Just Want The Souls?
An alternative with boss souls is to consume them, giving the player a certain amount of souls. The Soul of Sif rewards players with 16,000 souls if they decide to consume the soul rather than turn it into an item. Players can also give the soul to Kingseeker Frampt, though this only gives players about 4000 souls. When it comes to why a player would want to make a boss item rather than just take the levels, there are a few pros and cons to consider.
For one, the boss items are all unique and only obtainable using the boss soul, meaning that consuming the soul will prevent players from getting the unique equipment. That being said, doing a New Game Plus run allows players to get multiple items through multiple different playthroughs of Dark Souls. For a single playthrough, however, it really comes down to whether or not the unique items obtainable with the Soul of Sif are worth losing out on the levels they'd get from consuming the soul.