*Important* This mod is no longer a work in progress- it has progressed to the point that I have reached a minimum level of satisfaction with it. As such, all permissions to complete my work and claim it as your own are now revoked.

Installation:
Manual - Download the file, and extract the .esp file from the archive into your Data folder.
(Most commonly found at OS:C>Program Files (x86)>Steam>steamapps>common>skyrim>Data)
Using the game's default launcher, make sure DiabolusUrsusBlockPerks.esp is checked.

Incompatibilities:
I tried to keep modification of vanilla aspects to a minimum, but any mod that modifies the perks in the Block perk tree or the TorchBashPerk will be incompatible. Whichever mod is loaded lower in the load order will take priority.

Changes to the Block Skill:

Parry (Shield Wall): Five levels, at 0, 20, 40, 60 and 80 block.
Blocking with a shield or weapon is 10, 20, 30, 40 and 50% more effective.

Shield Branch (These perks require a shield to be equipped to function.)

Elemental Protection: Two levels, at 25 and 50 block (Requires at least one level of Parry.).
Level 1 reduces incoming fire, frost and shock damage by 25% while blocking and level 2 reduces them by 50%.

Deflect Arrows: One level, at 30 block (Requires at least one level of Elemental Protection).
The vanilla Deflect Arrows perk. If someone lends a hand in the future with scripting or shows me what needs to be done, this is subject to change and improvement.

Deadly Bash: One level, at 50 block (Requires Deflect Arrows). Bashing does 5 times more damage.

Weapon Branch (These perks require a shield NOT to be equipped to function.)

Counter Stroke: Two levels, at 25 and 50 block (Requires at least one level of Parry.)
Level 1 provides a 10% chance to deal ten times incoming damage to an attacking enemy while blocking with a weapon. Level 2 provides a 15% chance.

Disarming Impact: Two levels, at 30 and 60 block (Requires at least one level of Counter Stroke.)
Level 1 provides a 20% chance to disarm an opponent of any level when bashing with a weapon and level 2 provides 40%.

Quick Reflexes: One level, at 50 block (Requires at least one level of Disarming Impact.) Slows time for 2 seconds when an enemy power-attacks. This should be the same as the vanilla perk, though if it could be made a bit less buggy that would be ideal. (No infinite time-slow, etc.)

Utility Branch (These perks work regardless of whether or not a shield is equipped.)

Defensive Alacrity: One level, at 30 block.
The vanilla Block Runner perk. If someone can show me how to create different movement speeds depending on whether or not a shield is equipped, that would be very appreciated.

Power Bash: One level, at 60 block (Requires Defensive Alacrity.)
The vanilla Power Bash perk. It won't work when implemented otherwise, for reasons unknown. At this time it serves as a means of getting both the Violent Impact and Disarming Impact perks to work properly at the same time.

Violent Impact: One level, at 100 block (Requires Power Bash.)
Power Bashing with a shield or weapon has a 20% chance of knocking most opponents down. This is accomplished by a 1 second Paralysis effect, so enemies immune to Paralysis will be impossible to knock down.

Torch Specific Perks
Warding Flames:
Bashing with a torch now applies a 1 second fear effect to all living enemies.
This was originally intended to be a purchased perk with a longer duration, but the vanilla TorchBashPerk overrides all custom ones for reasons unknown.