Mace+6
Forest of Fallen Giants
Go to the Lost Bastille to collect the remaining Large Titanite Shards for upgrading the Mace to +6. The shortest path to the Lost Bastille is from the crow nest behind the arena of the Pursuer. The arena can only be accessed by using the Soldier Key, dropped by the Last Giant.
The Last Giant
This boss is not particularly difficult for an SL1 character. Use the Hand Axe or the Mace+4. Stay underneath the boss, get in one or two hits on a leg, then move to the other leg. Rinse and repeat. Watch out for the stomp attack. Defeating the Last Giant would reward you with the Soldier Key, an item required to unlock the path to the Pursuer.
Defeat the Last Giant, exhaust the dialogue of Melentia, rest at a bonfire, and she would relocate to Majula where she would sell an unlimited amount of Lifegems. Have 18,000 souls to purchase all three Brightbugs from Melentia. Brightbugs will be useful against the more difficult bosses later in the game.
The Pursuer
Use the Soldier Key to open the path to the Pursuer. The Pursuer can be cheesed by using the ballistae. In NG+0, a ballista can kill the Pursuer with two shots. In higher NGs, you require many more shots from a ballista. The Pursuer's attacks can be avoided by strafing to your right. The charging slash attack can be avoided by running or walking around the Pursuer and to your right. Bait the charging attack, strafe to your right, get in a hit, and move away. Rinse and repeat. Defeating the Pursuer would reward you with the Ring of Blades. Equip the ring to boost your physical attack. Interact with the crow nest found behind the arena of the Pursuer and you would be transported to The Lost Bastille.
The Lost Bastille
Lost Bastille: Dull Ember and Large Titanite Shard x 5
From the Tower Apart bonfire, open a chest to collect the Dull Ember. You will give the ember to McDuff to allow him to infuse melee weapons. On your way to McDuff's workshop you will encounter Lucatiel. Don't interact with her at this location. You need to properly follow her quest line in order to obtain the Ring of Steel Protection+1.
Collect Large Titanite Shard x 4 on your way to McDuff's workshop. Use a gun powder barrel to break a wall, revealing the McDuff's Workshop bonfire. Exhaust McDuff's dialogue, give him the Dull Ember, use a torch to light the sconce in his workshop, rest at the bonfire, and McDuff should be smithing in his workshop. Purchase a Large Titanite Shard from McDuff and upgrade your Mace to +6. Purchase another Large Titanite Shard x 6 to upgrade the Light Crossbow to +6 as well. Spend at least 14,000 souls by using McDuff's services to upgrade your weapons. Then exhaust his dialogue and he would gift you a Titanite Slab, which should be your second slab. Remember to infuse and upgrade your weapons at McDuff's workshop, instead of using the services of Lenigrast, and you would shortly fulfill the condition for receiving a Titanite Slab from McDuff.