Poncle has published a guide for Vampire Crawlers detailing how to evolve weapons. Players can combine a weapon with a specific card type at an Evolution Statue or through chests and boss drops.
Weapon evolutions require specific card combinations
The Magic Wand evolves into Holy Wand with a Tome card. The Fire Wand becomes Hellfire with Spinach. The Whip turns into Bloody Tear with a Heart card. The Knife evolves into Thousand Edge with a Bracer card. The Cross becomes Heaven Sword with a Clover card. Santa Water evolves into La Borra with an Attractorb card. The Axe becomes Death Spiral with a Candle card. Garlic evolves into Soul Eater with a Pummarola or Pummadora card. King Bible becomes Unholy Vespers with a Spellbinder card. Runetracer evolves into NO FUTURE with an Armor card. Shadow Pinion becomes Valkyrie Turner with a Wings card. Gatti Amari evolves into Vicious Hunger with a Stone Mask card.
Some evolutions require combining two weapons. Peachone and Ebony Wings evolve into Vandalier without extra cards. Phiera Der Tuphello and Eight the Sparrow evolve into Phieraggi with a Tirajisú card. Pentagram evolves into Gorgeous Moon with a Crown card. Song of Mana and Skull O'Maniac evolve into Mannajja.
The guide comes from Videogameschronicle. Poncle has not confirmed any additional details about future updates or changes to these evolution paths.
Source: Vampire Crawlers, VideoGameChronicles