Okay, here is a couple builds I will try to keep them good and playable from 1-10 levels.
Keep in mind without knowing the groups playstyle and dynamics it is hard to put together builds beyond purely a mechanical perspective. Going to try and keep in mind the Roguish flavor though
These builds tend to focus more on the Gish side of things in not spending feats to enhance spell DC and such.
Human Beguiler 6/Swiftblade 4 [spoiler]
Stats: Int of course if prime really followed depending on your focus and concept. Stats set below reflect a better than average in all areas character. Easily points could be shifted to enhance or sacrifice for more focused build.
Str: 14 (6) - for encumbrance and possible Power Attack (even if only from Heroics)
Dex: 14 (6)
Con:12 (4)
Int: 16 (10)
Wis: 12 (4)
Cha: 12 (4)
Points spent (34)
Could easily sacrifice more Con if not worried about Fortitude save or even more from other stats if not worried about skill bonuses and other saves.
Feats: Human) Dodge or Expeditious Dodge (Races of the Wild)
Flaw) Faerie Mysteries Initiate (good background roleplay fluff here) (Int to HP)
Flaw) Versatile Spellcaster
1st) Heighten spell (If Versatile Spellcaster Trick is allowed)
3rd) Mobility
6th) Darkstalker (if you are going to be stealthy then be it
)
9th) Arcane Strike?? [/spoiler]
Whisper Gnome Beguiler 6/Swiftblade 4[spoiler]
Stats: Int of course if prime really followed depending on your focus and concept.
Str: 10 (4) -- with Racial -2
Dex: 16 (6) +2 Racial
Con:16 (6) +2 Racial
Int: 16 (10)
Wis: 12 (4)
Cha: 10 (4) -- with racial -2. Prefer to not get penalties on UMD but if not put points elsewhere.
Points spent (34)
Feats: Flaw) Dodge or Expeditious Dodge (Races of the Wild)
Flaw) Versatile Spellcaster
1st) Heighten spell (If Versatile Spellcaster Trick is allowed)
3rd) Darkstalker (if you are going to be stealthy then be it
)
6th) Mobility
9th) Arcane Strike??
[/spoiler]
Traits: Didn't look at traits.
Skills: You will have tons of skills to put in stealth, social, spot, listen, search, disable, ect... depending on your desires and parties needs. If you go Whisper Gnome your stealth will can be off the chart for your level or you could use the racial bonus to free up skill points for other areas.
Gear: Various buff and utility wands like Heroics, cures, protection from X, Wraithstrike. Preferably with wand chamber in weapon. Circlet of Persuasion gives good boost to lots of skills too. Metamagic Rods.
Tricks: If your DM allows, the combo of Heighten Spell and Versatile Spellcaster should allow you to overcome some problems with lost caster levels. Spend two spells to produce a heightened one of one level above. Nifty trick but expensive in both feats and spells if used much. As a DM I'd allow it but... I'm not. If allowed you could have 2nd level spells at 1st level but by 10th it would simply allow to to cast 4th level spells as you would as a pure Beguiler despite two lost Caster Levels.
If your DM does not allow this Trick then Versatile Spellcaster is probably still worth it in my experience.
Will your DM allow Eclectic Learning (warmage Alternative class feature for Advanced Learning) for the Beguiler's Advanced learning? It would open a LOT of options. How does your DM run the Extra Spell feat?