Grimstaff
Explorer
I can't say I agree with the charisma-based spell-casting. The archetype of the Eldritch Knight is definitely wizard-based, with all the versatility that entails. Try looking at your Eldritch Knight core class from the standpoint of where the character would be at 10th level built in the RAW:
RAW version: Evok5/Fighter1/EldKngt4; BAB +7; Fort+7 Ref+2 Will+5; Spells 5/5/4/4/3; Feats 9(Summon Familiar, Scribe Scroll, +4 General, +2 Fighter, +1 Metamagic).
Core Version: EldKngt10; BAB +10; Fort+7 Ref+3 Will+3; Spells 3/3/3/3/0 (Known 6/4/4/4/2); Feats 7 (3 Bonus +4 General).
The RAW version has way more spells, with the versatility of an Int-based arcane spell user, and gets 2 more feats overall, a higher Will save, and only suffers +3 BAB in exchange.
Lets look at 20th lvl:
RAW: Evok9/FIghter1/EldKngt10; BAB +15; Fort+12 Ref+6 Will+9; Spells 5/5/5/5/5/5/5/4/4/3; Feats 12
Core Version: EldKngt20; BAB +20; Fort+12 Ref+6 Will+6; Spells 4/4/4/4/4/4/4 (Known 6/5/5/5/5/5/4); Feats 12
At top level, the core version finally catches up on feats, has a BAB only +5 higher, and still suffers greatly on spells per day. Note that the BAB gap can be further closed by sacrificing 9th level spells: Evok6/Fighter4/EldKngt10 gives you a +17 BAB, 2 more feats (including weapon specialization) and still offers many more spells than the Core class.
Try a Core Class set up with the Cleric BAB progression, 2 good saves (Fort and Will), Bonus Feats at 1,5,9(weapon specialization),13,and 17, and staggered spell level access (2nd at 4th, 3rd at 7th, 4th at 10th, 5th at 12th, 6th at 15th, 7th at 18th, 8th at 20th) and you should get a pretty close simulation of what the RAW version achieves.
RAW version: Evok5/Fighter1/EldKngt4; BAB +7; Fort+7 Ref+2 Will+5; Spells 5/5/4/4/3; Feats 9(Summon Familiar, Scribe Scroll, +4 General, +2 Fighter, +1 Metamagic).
Core Version: EldKngt10; BAB +10; Fort+7 Ref+3 Will+3; Spells 3/3/3/3/0 (Known 6/4/4/4/2); Feats 7 (3 Bonus +4 General).
The RAW version has way more spells, with the versatility of an Int-based arcane spell user, and gets 2 more feats overall, a higher Will save, and only suffers +3 BAB in exchange.
Lets look at 20th lvl:
RAW: Evok9/FIghter1/EldKngt10; BAB +15; Fort+12 Ref+6 Will+9; Spells 5/5/5/5/5/5/5/4/4/3; Feats 12
Core Version: EldKngt20; BAB +20; Fort+12 Ref+6 Will+6; Spells 4/4/4/4/4/4/4 (Known 6/5/5/5/5/5/4); Feats 12
At top level, the core version finally catches up on feats, has a BAB only +5 higher, and still suffers greatly on spells per day. Note that the BAB gap can be further closed by sacrificing 9th level spells: Evok6/Fighter4/EldKngt10 gives you a +17 BAB, 2 more feats (including weapon specialization) and still offers many more spells than the Core class.
Try a Core Class set up with the Cleric BAB progression, 2 good saves (Fort and Will), Bonus Feats at 1,5,9(weapon specialization),13,and 17, and staggered spell level access (2nd at 4th, 3rd at 7th, 4th at 10th, 5th at 12th, 6th at 15th, 7th at 18th, 8th at 20th) and you should get a pretty close simulation of what the RAW version achieves.