There's a blacksmith that can upgrade +10 weapons into lightning ones. But keep in mind that lightning removes all scaling and splits your damage into 2 types (physical and lightning). Claymore benefits from dex and str so if you have both leveled up, a +15 version will deal more damage and could be enchanted.. If you're building primarily dex, I hope you're saving your titanite slabs for +15 weapons, since pure physical will outdamage lightning-infused in most cases. Lightning damage only scales with upgrade level and base damage, no stats. Anyway, you'll want something with good base damage and little to no scaling. Gargoyle halberd, for example. Otherwise, take it down physical to +15.
Yes, lightning weapons are undeniably good in Dark Souls, especially for new players and in the early to mid-game. They offer a potent damage type that bypasses the need for significant stat investment in Strength or Dexterity, allowing you to focus on Vitality and Endurance.. Lightning damage in Dark Souls 3 is tremendously helpful against all kinds of enemies, including the mighty Lords of Cinder. Here's how all stack up.