Welcome to DDO.
In general, attempting to mix melee DPS with caster DPS will usually result in a build which isn't good at either. DDO uses a
heavily modified version of the 3.xE ruleset, which tends to encourage specialization over generalization, IMO, particularly in the late-game stage. This is particularly true of arcane casters; while DDO contains the
Eldritch Knight PrE, it's pretty weak DPS-wise compared to "real" melee PrEs. If you want to add trap skills as well, that requires either a rogue or Artificer splash, which limits your multiclassing options.
[PrE = Prestige Enhancements: in PnP terms, think of them as a hybrid between 2E's class kits and 3E's prestige classes. PrEs are where a lot of the power of classes comes from.]
That said, there's a pretty big gap between what's considered optimal vs what is viable for most content. And if you have
Harper (free to VIPs), that opens up some interesting INT-based options for gishes. The recent buffs to Kensei make, say, wiz 12 / ftr 6 / rog 2 (or wiz 13 / ftr 8 / rog 1) a much more viable combo than it was before. If you're not wedded to TWF in med/hvy armor, I think wiz 15 / bard 3 / rog 2 works well:
SWF w/rapiers for melee, lvl 8 wiz spells for spellcasting, rog splash for trap skills & Evasion. If you don't
really need trap skills, I would consider wiz 12 / rgr 5 / ftr 3: you miss out on the tasty crit bonuses from Kensei or Tempest, unfortunatel, but should be able to create a fairly sturdy toon otherwise. Alternatively, if you're not wedded to arcane casters, you can do something with druid hybrids, who have some useful spells with no DCs (e.g., Ice Storm, Creeping Cold & Gtr CC).