Leather armour is questionable at best. Plain leather doesn't offer much in terms of protective value. Then there's hardened leather (boiled leather aka 'cuir bouilli' ) which is typically more demanding to make than it's worth, and you'll still have better alternatives for protection. Another critical disadvantage to using leather as your main component in armour, is that you can't repair it. Damaged leather is damaged, but metalwork and cloth can be repaired with relative ease. It is obvious that Light Armour is usually worn by scouts, and people who fight from range. Leather Armour still offers some protection though. You'd be surprised with the difference it makes. Even cloth armour... A proper quilted arming dublet will stop a serious stab even though it's only made of linen. It might hurt, but you'll live.
That being said, it's obviously easy to harm someone wearing light armour, and the best way to do it is by using a sharp weapon. As light-armour wearers, they are more swift, since they have less weight on their body, thus they don't get tired that easily, so it's be a bad idea to chase them with a mace or any other similar weapon.
Depending on your Class, you might get to use a shield. Light(er) shields are often used just for a little more protection, and that is obvious. For someone who isn't trained as a warrior, yet needs to fight, it is enough for them to be able to protect their family from 2-3 people. (For example, minstrels)
A shield might also be your raison d'etre. (Looking at you, Wardens. For a Warden, their shield is everything. A warden fighting with spears and javelins, fights like an ancient greek warrior from the kingdom of Macedonia. Wardens are like warriors of a phalanx. Their shield and spear is everything for them, and is used both defensively and offensively. Bring a bunch of Wardens to the party, and you'll get an impenetrable shield-wall.
For someone like a Guardian, their shield is more of a weapon, and a tool for taunting opponents an guarding allies, than for guarding themselves. Heavy Shields can pretty much withstand most hits, and be used as a secondary weapon. (Thanks Newton!😊)