okay so, you basically reverse the mechanical formula for weaponry and armour
so in 5e a weapon's to-hit is [dice roll]+PB+Modifier, and an armour's AC is [static value]+Modifier(other than heavy armours), right?, so weapons functionally have a modifier on every attack roll and AC is a fixed set value
my suggestion is to swap the weapon's [dice roll] and armour's [static value] to make weapons with [static value]+PB+Modifier and armour with [dice roll]+Modifier, each weapon you have ends up with a fixed to-hit value (a longsword might have [fixed 8]+PB 4+STR 5 and would thus always attack with a to-hit value of 17) and you make a dice roll when attacked to determine how well you defend yourself, getting a nat 1 to defend is the equivilant of attacking someone with a nat 20.
OK, I'm feeling brain-dead this morning (one of those days where I wish I hadn't given up caffeine), so lemme see if I got it. For the time being, I'm going to ignore the variable value based on weapon, at least until we've decided what those values are, and assume that the fixed value is 10. If I'm understanding this correctly, the GM won't be rolling for combat. Which is fine by me.
So let's assume two different Bad Guys here, so we can have a look at different power levels. A bandit is CR 1/8, has +3 to attack (+2 PB, +1 Str), and has AC 12 (+1 Dex, +1 leather). A Warlord is CR 12, has +9 to hit (+4 PB, +5 Str), and has AC 18 (plate armor, +3 Dex not included but might be important later).
The PC has an
Attack Value of (10 + (PB +4) + (Str +5)) 19, and would need to roll under a 19 to hit? Which would make it
really darn easy to hit. So I'm getting something wrong here. Or... Would it be 19 - the armor? Hitting the bandit would be (19 - 2) 17 or less, while hitting the warlord would be (19 - 8) 11 or less. If we assume a 1st-level PC with AV 15 (10 + (PB +2) + (Str +3). Against the bandit, they'd have to roll a (15 - 2 from leather) 13 or lower; against the warlord, they'd have to roll an 15 - 8 from plate) 7 or lower. These are base numbers and don't take any other bonuses, like Weapon Specialization or magical weapons, into consideration; all of these would increase the base AV up there.
These numbers seem more reasonable to me, but someone who is better at math than I am might want to run the numbers and see how this compares to 5e or other editions. It seems like you might be somewhat less likely to hit in this version.
The different weapon values, while possibly realistic, would likely be difficult to decide. A knife is good at getting past defenses but not so good at getting past armor, but a mace has a lot of force behind it that can push past a lot of defenses but might be more easily blocked, and so on. That said, I could see feats (or maneuvers) that are "Weapon Expert" where your knowledge with a particular weapon increases your attack value with it by 2 (and may be stackable, if you want to take the feat more than once), and certain the Weapon Specialization/Mastery abilities I gave to the fighter would increase the AV by even more.
Now onto defense. Would the
Defense Value be based on the character or the foe? In other words, when we write up a creature's statblock, would it include their DV in it, or is this something that is entirely dependant on the PC? In D&D, almost all of your defensive ability is based on static AC, with only a very small number of things that alter that. In Level Up, a lot of weapons have the parrying quality, which means you get to add a d4 to your AC if you're wielding that weapon--but that list of weapons include things like quarterstaffs, so even a wizard can try to parry.
In other words, if the bandit is attacking me, do I need to roll against something on
their sheet or on
my sheet?
If it's on
their sheet, then the DV should be based on their weapon skill. So a bandit's AV could be (X - 3), whereas the warlord's AV could be (X - 9). So is X a static number and if so, what?
If it's on
your sheet, should it be based on your AC alone, your AC + things like parrying ability[1], or on a static number + your Dex, PB, and/or other things like shields, with armor being used as damage resistance?
Of if it's on your should, would it be based on a static number (your AC + whatever or your Dex + whatever) - their weapon skill, so if your DV ends up as a 15 (plain ol' chainmail alone) and the creature's DV is 3, when you roll to defend and you roll 11, you would say you made it by four and that means you beat their DV?
[1] In Level Up, certain weapons have the Parrying trait; 1/turn you can add a d4 to your AC. This includes quarterstaffs, so even your wimpy wizards can parry. In D&D, parrying seems to just be equal to your PB most of the time and is more a special ability than a weapon trait.
