I dunno if this will work, but there's a Book II "trick" they might help in this situation:
In Book II, whenever my character has to cross a lava field, I would simply take off my boots and leggings - doing that would protect them from any harm (and the rest of my armor is unaffected by the lava). Similarly, any situation where I was dealing with something that I knew was going to explode adjacent to me, I would simply take off all my armor - putting armor in the inventory protects it against damage from explosions.
Thus, it seems to me, you could strip down to you bare essentials, and put all of your armor in your inventory, if you want to fight Acid Grubs hand-to-hand. That still won't protect your weapon from exploding Grubs. But it should at least protect your armor from destruction by exploding Grubs.
I dunno if this works in Book I, though - I've never tried it...
It does work. It's just more convenient if you can kill them from a distance to avoid all the mouse clicks (since changing armor takes no game time in Book I, it's not a problem from that perspective).