The last line of ToolHelper.isToolEffectiveAgainst uses the vanilla ItemStack#func_150997_a method to get the tool's break speed for the block, but it should probably use the Forge-provided Item#getDigSpeed method instead since this is used for the actual break speed calculations when breaking blocks.

Good call, thanks for letting me know about that.

Thanks for the quick fix. This should allow my custom swords to show as effective tools for Cobwebs.

Released here: https://github.com/squeek502/WailaHarvestability/releases/tag/v1.1.5