Looking through the alphabetical list of magic items (DMG p150) I see it includes:
- Ammunition, +1, +2, or +3
- Armor, +1, +2, or +3
- Weapon, +1, +2, or +3
But there don't appear to be any generic spellcasting implements. I had expected perhaps a "Holy Symbol, +1…" or even "Implement, +1…". There is the occasional specific wand, rod, etc. but most are of the "finite charges" variety, and are only really for the more wizardy kind of spellcaster.
Does 5th edition have generic spellcasting implements that provide a bonus to the attack (or saving throw DC) made with that implement? Does it have any holy symbols or totems that include this? If not, would homebrewing such a thing have a significant effect on balance?