HP: 12
AC: 19 (10 without armor), -6 armor check penalty for DEX skills and 35% ASF
HP is only 10: 8 from d8, +2 CON.
AC: 18 (10 - 1 DEX + 9 fullplate), touch 9, flatfooted 18, ACP -6 (STR and DEX skills)
We have a Shield for +2 AC too, but only gets used with flail or Lance or shortsword.
Attack: +3 (1 BAB, 2 STR) with Light Flail, +3 (1 BAB, 2 STR, 1 Masterwork) with Falchion, Ranged +0 (1 BAB, -1 DEX)
Attack with Falchion is +4.
Damage: 2d4+1 (Masterwork Falchion), 1d8 (light flail), 1d6 (shortsword), 1d8 (Composite Longbow)
Damage with falchion is 2d4+3, 1d8+2 for Flail (becomes +3 if two-handing) and Bow, 1d6+2 for shortsword.
PF Power Attack means -1 to hit, +2 damage one-handed, +3 damage two-handed, but we can only take -1, and then another -1 for every 4 BAB (so max -6 to hit for +12/+18 damage at lv 20).
So our best hit is Falchion +3 (2d4+6/18-20 x2).
Strength: 14 + 0 = 16 (+2)
Bonus is right, total isn't.
Skills:
Diplomacy: 8 = +5 (CHA), 1 rank, 2 background bonus
Handle Animal: 6 = +5 (CHA), 1 free background rank
Knowledge (Arcana): 2 = +1 (INT), 1 rank.
Knowledge (History): 3 = +1 (INT), 1 rank, 1 background bonus
Knowledge (Nobility): 1 = +1 (INT) not trained
Knowledge (Religion): 2 = +1 (INT), 1 rank
Perform (Strings): 6 = +5 (CHA), 1 rank
Ride: 2 = +1 (DEX), 1 rank
Sense Motive: 1 = 2 ranks, -1 (Wisdom)
Most of these are class skills. In PF, you don't gain the x4 skill points on first level, and neither do cross class skills cost 2 points or have a lower cap. Instead, you receive a +3 bonus if you have at least one rank with a skill that is in-class, and the max rank is equal to your HD. Cunningly, this means the values from 3.5 and PF largely track, as you'd put 4 ranks in 3.5 and put 1 rank with a +3 bonus in PF.
Concentration is a CL + Casting stat check as well, not a skill. So 1d20+8 for us (1 Cal + 5 CHA + 2 Focused Mind).
So:
Diplomacy: 1 + 5 (CHA) + 3 (class) +2 (background) = +11
Handle Animal: 1 (bonus) + 5 (CHA) + 3 (class) = +9
Knowledge (Arcana): 1 + 1 (INT) + 3 (class) = +5
Knowledge (History): 1 (bonus) + 1 (INT) + 3 (class) = +5
Knowledge (Nobility): 1 (bonus) + 1 (INT) + 3 (class) + 2 (Noble Scion) = +7
Knowledge (Religion): 1 + 1 (INT) + 3 (Class) = +5
Perform (Strings): 1 (bonus) + 5 (CHA) = +6
Ride: 1 - 1 (Dex) + 3 (class) = +3
Sense Motive: 1 - 1 (Wis) + 3 (class) = +3
Rank + stat + class skill bonus + misc. Simple and clear, ya? Scion of War, aka Noble Scion, makes Nobility a class skill and gives +2 to it, fittingly enough.
I don't think he needs that background bonus to Diplo
If you want to change it to a bonus rank, like the others, then we can get +1 HP from favored class.