For what it's worth, I ran some damage simulations, assuming a single target infinite series of attacks and all combination skills.
All skills, assuming no loss on miss: about 5.2 average damage.
Reset on miss: Bonus linear with accuracy, so 2.6 at 50% accuracy.
Reduce by 1 on miss: approximately linear with accuracy up to 4 damage at 50% total accuracy, then leveling off to a maximum of ~5.2 at 100%
As a comment, I think defense is already quite strong, and the better balance option would be no resetting (possibly with a reduction to the actual bonus if it needs a nerf)
Note for whoever looks into this. Bob and I discussed Combo Attack not resetting awhile ago and this is a bug. However if combo attack feels too strong, I think the -1 step on miss is a really good compromise that doesn't completely neuter the skills.
"Compromise" fix has been applied on dev that reduces combinations by one step on a miss instead of deleting entirely (obvious exception: a miss after Combination 1 deletes the effect entirely).