So, in order to answer your question about stab/crush/slash weapons I'll explain how monster weaknesses work with OSRS Gold an example. Steel dragons are afflicted by Water spells. This means you'll be able to get the most accuracy with Magic (Water spells specifically.)
Also, if a monster cannot Crush or crush, such as Jadinkos that means melee is the fastest method of attack against them in addition, Crush is the most efficient style. Contrarily, Range or Mage will have less accuracy. (Although at high levels, your gear is generally good enough that there's not much difference.)
In conclusion, keep your Dragon scimitars do not purchase any additional melee guns. They're sufficient for all things that are ineffective against melee. Likewise, stick to dual wielding range and magic. I'm assuming that you don't own anti fire potion therefore, avoid dual handling. Also, dual wielding allows the use of a shield and the Rejuvination/Resonance abilities.
The same applies to elementsal spells. Personally, I've got many elemental runes stashed up, so I always just use the weaknesses of the monster. The choice is yours, but the chances are you'll hit it well with air spells.
If you're playing in EoC the game, you don't be required to Cheap RuneScape Gold pray for protection at all. The healing powers of Rejuvenate, Guthix's Blessing Ice Asylum as well as Regenerate along with some affordable food are usually sufficient. Don't spend money on them unless you are planning to use Soul Split, Turmoil, or the Zealot boosted normal prayers.