[RPM] buffing weapons to do damage for a duration
 

I am about to play a MH game as a witch, and one of the stunts I want to be able to pull off is buffing a weapon. It appears that the most obvious route, adding a damage modifier and a duration is both illegal and overpowered. So I'm trying to figure out something else.

Is the proper way to do this 'add an innate attack'? either follow through or linked?

For example, making a knife blaze with fire could be built as follows:

Greater Create Energy(6) + Added attributes 2d Burning attack (melee C,1 -20%, linked +10%) (9)+ duration 10 minutes (1) = 48 (16*3)

On the other hand, a hand gun with rof 3 recoil 2, range 200/2000 enchanted especially to destroy undead, but that only works on penetrating their flesh, would look like this:
Lesser Destroy Undead(3) + Added attributes 3d toxic attack (follow up on rapid fire 3 +50% recoil 2 -10% range *20 +40%,only vs. undead -20%) (19)+ duration 10 minutes (1) = 23

Am I building this right? or should I be using bestow a bonus or the damage-duration combination instead? And should I be adding the weapon weights?

Re: [RPM] buffing weapons to do damage for a duration
 

Bestows a Bonus is the canonical way to do it. See this post.

Re: [RPM] buffing weapons to do damage for a duration
 

Note that, per the usual GURPS rules, it's a special effect to change every +2 to damage into +1/die. That is, if your weapon does 5d+2 damage, and you pay for "a +4 damage bonus," it's legit to interpret that as "a +2/die damage bonus" and call it a net 5d+12.

As for weapon weight, I'd say that yes you do, because I can't picture a spell that increases damage done that doesn't effect a physical change in the weapon. Even just "it swings faster and hits harder" is a physical change. (And trying to get around that by saying something like, "It has a mystical field that causes instant necrosis in the wound, inflicting more damage," is just an argument for paying for the weight of your victim instead!)

BTW, it's worth mentioning that several people here have argued that Bestows a Bonus/Penalty should "flatten out" rather than continue to double, and while I don't plan on retroactively changing the existing mechanic, I do support this as an optional rule -- one that I'm planning to work into a future supplement (as an official optional rule). Basically, at +/-3 or higher, use a flat 4*(D-2) for Narrow, 8*(D-2) for Moderate, and 20*(D-2) for Broad, where "D" is the degree of bonus or penalty.

Re: [RPM] buffing weapons to do damage for a duration
 

Um Are you Sure of the numbers? 'cause this contradicts the Dice adds that +3 is +1d and +7 is + 2d not +2 and +4

Re: [RPM] buffing weapons to do damage for a duration
 

You're misreading me. I didn't say "every +2 becomes +1d." I said that "every +2 becomes +1/die" -- that is, +1 damage per die. And this is a standard thing for GURPS; see the rules for All-Out Attack (Strong) for the most common instance.

Re: [RPM] buffing weapons to do damage for a duration
 

That +2 can be converted to +1 per die is a huge revelation.

So instead of Swing +2, a fine broadsword can do Swing+1 per die... Nice.

Re: [RPM] buffing weapons to do damage for a duration
 

Damn, I likes this. That's a good idea, Hoss.

Re: [RPM] buffing weapons to do damage for a duration
 

"per the usual GURPS rules" - is this stated as a general rule anywhere or are we just supposed to infer it from the (sometimes stated and sometimes not) examples scattered through the rules. For example, it states this for All-out attack but does not do so for very fine weapons (where it merely says +3 for cutting and impaling attacks).

Re: [RPM] buffing weapons to do damage for a duration
 

Actually, you're completely right that I was a bit too glib there. It would have been far more accurate for me to have said this . . .

Most GURPS examples of applying an external force that makes a weapon hit harder (All-Out Attack, Committed Attack, Mighty Blows) -- as opposed to intrinsic damage modifiers such as weapon quality, base damage adds, etc. -- treat each flat +2 to damage as equivalent to +1/die. I would consider a "Bestows a Damage Bonus" modifier to be such an external force, and allow it to use the same rule.

. . . so please consider this my more carefully voiced thoughts on the matter.

Re: [RPM] buffing weapons to do damage for a duration
 

Thanks! I'm sure you worked that out in your head ages ago and it just makes sense to you, but we were having a bit of trouble following.

As far as 4*(D-2) for a Bestows a Narrow Bonus goes, you're not worried about the scaling? Is +8 worth twice as much as +4, or more than that?

Re: [RPM] buffing weapons to do damage for a duration
 

a +4 bonus is 4*(4-2)=8. a +8 bonus is 4*(8-2)=24. Your general instinct is correct, but you need to remember to subtract the 2. The curve in general looks like this:

+1:1
+2:2
+3:4
+4:8
+5:12
+6:16
+7:20
+8:24
+9:28
+10:32

and so forth

Re: [RPM] buffing weapons to do damage for a duration
 

Ah, that's right, isn't it? That actually looks pretty good, thank you.

Re: [RPM] buffing weapons to do damage for a duration
 

This has definite ramifications for people who are able to cast RPM damage buffing spells on particularly brawny recipients

Re: [RPM] buffing weapons to do damage for a duration
 

Or RPM-buffing recipients to make them brawny before then buffing their weapon.