"Does your character NEED to be a bladelock? If you go tomelock you can get shillalah for a cha powered staff, and celestial warlocks can do extra damage with the green flame blade cantrip, which isn't compatable with the bladelock's second attack anyway. Pick up Moderately Armoured feat for medium armour and shield proficency early on."
This could be a viable option - the switch to the staff and the book would represent the character's shift from a warrior (if you start with a level of fighter) to one fighting using the Celestial Law (the book of shadows).
Ugh.... the age old How do I play a hexblade X? By playing a Tomelock! answer. Don't get me wrong I get the point its a workable Idea (so is going Hexblade patron instead) I just hate it when the reply to asking how to do one thing results in "do something else". In fact, the OP pre-imbed that a bit.
"So I am envisioning a former mercenary veteran who was reasonably honorable, but became involved with a very, very angry angel he now is instructed by."
"4. I am going blade pact. For thematic reasons, thinking staff as main weapon and likely polearm master at some point. Not optimal perhaps? but its OK. I imagine the pact weapon changing appearance for different spells and functions. Iron on end looks like fist when smiting, hand open and holds glowing orb when casting light, etc."
"Can't wait to hear up some ideas and recommendations!
The ONLY ONE I really don't want is "just play paladin."
It is not what I want to do. The image of a guy in a scale shirt with cloak, hood quarterstaff and arcane things is where I want to go!"
Now pact of the Tome might keep with that image but I feel like their is some investment in #4.
… Rant done.
Ok, Yes, I can see this working...
An alternate suggestion taking the same path. Human Variant: Magic initiate Druid, take Shillelagh
as one of your cantrips. Make your staff your pact weapon but you can still cast Shillelagh
on it and you can still be Hexblade.
Str:10 Dex:14 Con:16 Int:8 Wis:8 Cha:16 with Armor of Shadows 13, +2 dex = AC15
So one issue is the 1 turn delay. Round 1, cast mage Armor with Armor of Shadows and cast Shillelagh (1d8 +3 from Cha, Magic and doing two handed versatile damage with one hand) both are cantrips for you so this is 100% repeatable but you can't join the fight until round 2.
Pick up Moderately Armored at 4 means you can engage in round one, casting shillalah as a bonus action then attacking with the action, but at that level you really want hex and polearm master working. So you take polearm master and 1 round delay so that your doing more damage the rest of the fight... but your also taking more with your low AC15 until level 8 when you pick up Moderately Armored but can likely go striate to Halfplate AC15 +2 dex = AC17... if you can except the shield +2 then AC19.
That gets you up and running but now your level 8 BUT your still at 16 CHA because you have only used ASI for feats. So your REALLY going to need to take +2 CHA at lvl 12 & 16. Your one ASI behind, but after level 16 your actually better off, however your low AC and 1 round combat delay until lvl8 is 4 levels of real hurt between 4 and 8. If your only averaging lvl 7-9 characters I am not sure its worth it. If your playing to lvl 20 it is because late game levels take longer as a rule so you will be stronger a lot longer than you will struggle. At the same time higher AC means more at lower levels when enemy attacks are lower. Near level 20 you basically expect everyone to hit because to hit improvement out weights high AC.