Generally no. There are however weapons that are bad for certain alignments to wield.For example in 3.5 a sword can be enchanted to deal extra damage to creatures of the opposite allignment (so a 'Good' sword that only deals extra damage to evil enemies and is just a normal sword+1 against neutral or good enemies) and grant a negative level to anyone of the opposite alignment who tries to wield it (the character counts as 1 level lower for the purposes of levels based calculations and loses 5hp while also getting -1 on saving throws, attack rolls and skill and ability checks).And yes, theoretically if we were going to go full DnD there's no reason for GS to not use a sword enchanted like this as it would actively weaken any goblin that tries to use it while also never dulling or breaking under any ordinary circumstance (standard for all magic weapons and armour).To be specific, the ideal weapon for GS to use would be a Holy Axiomatic Bane (Humanoids, Goblinoid) Sword+1 (all magic weapons must be at least +1). Such a weapon would deal an extra 6d6 damage per hit to goblins of all kinds specifically and when wielded by a goblin would apply 3 negative levels to them.For reference a normal short sword does 1d6 damage, so this 'Goblin Slaying Sword' would deal 6 times more damage to goblins on each hit compared to what GS currently uses but be basically useless in the hands of actual goblins, actually weakening them significantly. It would also cost over 72,000 gold coins to buy custom made so GS could never afford a weapon like that.Alas, this is in DnD 3.5 and under the assumption that your setting is high fantasy and high level enough to have such powerful items be available so even if GS could afford it these types of things just aren't freely available in the setting of GS.