Remlits are normally quite docile, but at night they become feral thanks to a demonic power. If you transform Batreaux into a human, they'll no longer change when the moon comes out, making it safe to traverse the town at night. Zelda owns one of these as a pet. You can't kill them, but you can make them retreat with a few sword strokes.
This is the sword left in Skyloft by Her Grace, the goddess. It has sacred powers the hero can use against evil. Its guardian spirit, Fi, is the hero's servant and guide. Once you wake up after Zelda gets sucked down to the surface, follow Fi past a series of obstacles and into the Goddess Statue to access the Skyloft Shrine. At the heart of the shrine, withdraw the sword from its pedestal and it's all yours.
The Adventure Pouch holds all kinds of backup supplies for ambitious adventurers. For you, this means shields, bottles, and occasionally some other stuff as well... You'll receive it as a gift before you take your first trip down to the surface world. It can only hold a certain number of items at a time, so be sure to make good use of the Item Check in the Skyloft Bazaar to swap out items as you need them.
This is a basic Skyloft knight's shield. It's made of wood, so it burns and breaks easily. Upgrade it at the Scrap Shop to improve its durability. Owlan will give you one to start off your quest, but should it ever break you can purchase a new one at the Skyloft Bazaar for 50 Rupees.
Deku Babas don't have any eyes, but that doesn't mean they can't track you with... wait, they don't have any sense of smell or sound, either. Be careful not to let them bite you. Their buds are covered in a hard carapace, so if you want to cut them you'll have to slice them across their open mouths. Gold-colored ones are tougher and can open their mouths in multiple directions, so watch them carefully. The Beetle can also slice right through their stems, and they'll gobble down any Bomb Flowers you toss their way...
The Revitalizing Potion serves a dual-purpose. Not only does it replenish four units of your life meter, it also fully repairs your equipped shield's Shield Gauge! You can upgrade it at the Infusion Shop in the Skyloft Bazaar, as well as buy refills should you run out. It was kind of the old woman to leave this potion for you!
Bokoblins are more intelligent than your average monsters. They'll use their weapons to block your attacks, sometimes parrying your incoming blows. To defeat them, you'll have to strike from a direction they're not defending against. They are known to wield a variety of weapons, from rusty cleavers to clubs and hammers. Boss Bokoblins carry horns that they use to summon reinforcements. You'll have to take them out by detonating their watchtowers with Bombs to prevent them from calling in backup. They seem to appear in multiple color varieties as well.